ghc-bignum: bring in sync .hs-boot files with module declarations

Before this change `BIGNUM_BACKEND=native` build was failing as:

```
libraries/ghc-bignum/src/GHC/Num/BigNat/Native.hs:708:16: error:
    * Variable not in scope: naturalFromBigNat# :: WordArray# -> t
    * Perhaps you meant one of these:
        `naturalFromBigNat' (imported from GHC.Num.Natural),
        `naturalToBigNat' (imported from GHC.Num.Natural)
    |
708 |           m' = naturalFromBigNat# m
    |
```

This happens because `.hs-boot` files are slightly out of date.
This change brings in data and function types in sync.

Bug: ghc/ghc#18437
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
23 jobs for !3676 with bignum-ci in 330 minutes and 6 seconds (queued for 1 second)
latest detached
Status Job ID Name Coverage
  Lint
passed #391191
lint
ghc-linters

00:00:57

passed #391192
lint
lint-linters

00:01:00

passed #391195
lint
lint-submods

00:00:21

passed #391193
lint
lint-testsuite

00:00:16

passed #391194
lint
typecheck-testsuite

00:00:15

 
  Quick Build
passed #391196
x86_64-linux
hadrian-ghc-in-ghci

00:10:25

 
  Build
passed #391197
x86_64-linux
validate-x86_64-linux-deb9-hadrian

01:30:05

 
  Full Build
failed #391200
aarch64-linux allowed to fail
validate-aarch64-linux-deb9

03:16:03

failed #391201
armv7-linux allowed to fail
validate-armv7-linux-deb9

00:03:20

passed #391202
x86_64-linux
validate-i386-linux-deb9

01:34:38

failed #391209
new-x86_64-windows test allowed to fail
validate-i386-windows

00:02:33

passed #391199
x86_64-darwin
validate-x86_64-darwin

01:09:08

passed #391203
x86_64-linux
validate-x86_64-linux-deb9-debug

01:45:08

passed #391205
x86_64-linux
validate-x86_64-linux-deb9-dwarf

01:59:42

passed #391204
x86_64-linux
validate-x86_64-linux-deb9-integer-simple

01:21:04

passed #391198
x86_64-linux
validate-x86_64-linux-deb9-unreg-hadrian

02:42:23

passed #391206
x86_64-linux
validate-x86_64-linux-fedora27

01:37:36

failed #391208
new-x86_64-windows test allowed to fail
validate-x86_64-windows

02:51:58

failed #391207
new-x86_64-windows test allowed to fail
validate-x86_64-windows-hadrian

03:18:21

 
  Cleanup
passed #391210
x86_64-darwin
cleanup-darwin

00:00:11

 
  Packaging
passed #391211
x86_64-linux
doc-tarball

00:05:34

 
  Testing
manual #391212
x86_64-linux allowed to fail manual
hackage
passed #391213
x86_64-linux
perf-nofib

00:23:47

 
Name Stage Failure
failed
validate-i386-windows Full Build
Git branch:   13-1-stable
GO version: go1.13.8
Built: 2020-06-19T21:12:23+0000
OS/Arch: windows/amd64
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=7732 revision=6214287e version=13.1.0
WARNING: junit.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit status 1
failed
validate-armv7-linux-deb9 Full Build There has been a runner system failure, please try again
  on ghc-arm-2 KodJpU4V
Preparing the "docker" executor
Using Docker executor with image registry.gitlab.haskell.org/ghc/ci-images/armv7-linux-deb9:6223fe0b5942f4fa35bdec92c74566cf195bfb42 ...
Authenticating with credentials from job payload (GitLab Registry)
Pulling docker image registry.gitlab.haskell.org/ghc/ci-images/armv7-linux-deb9:6223fe0b5942f4fa35bdec92c74566cf195bfb42 ...
Using docker image sha256:a0e2fabed2c062215178ec16a47c9762f74e49a6720a11685b56d10e04ddffb9 for registry.gitlab.haskell.org/ghc/ci-images/armv7-linux-deb9:6223fe0b5942f4fa35bdec92c74566cf195bfb42 ...
Preparing environment
Uploading artifacts for failed job
ERROR: Job failed (system failure): Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running? (docker.go:773:120s)
failed
validate-aarch64-linux-deb9 Full Build
Uploading artifacts...
ghc-aarch64-linux-deb9.tar.xz: found 1 matching files

junit.xml: found 1 matching files

performance-metrics.tsv: found 1 matching files

Uploading artifacts to coordinator... ok
id=391200 responseStatus=201 Created token=1H3FunRf
Uploading artifacts...
junit.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=391200 responseStatus=201 Created token=1H3FunRf
ERROR: Job failed: exit code 1
failed
validate-x86_64-windows Full Build
GO version:   go1.13.8
Built: 2020-06-19T21:12:23+0000
OS/Arch: windows/amd64
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=300 revision=6214287e version=13.1.0
junit.xml: found 1 matching files and directories

WARNING: Failed to load system CertPool: crypto/x509: system root pool is not available on Windows
Uploading artifacts as "junit" to coordinator... ok
id=391208 responseStatus=201 Created token=yczL8azK
ERROR: Job failed: exit status 1
failed
validate-x86_64-windows-hadrian Full Build
GO version:   go1.13.8
Built: 2020-06-19T21:12:23+0000
OS/Arch: windows/amd64
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=5072 revision=6214287e version=13.1.0
junit.xml: found 1 matching files and directories

WARNING: Failed to load system CertPool: crypto/x509: system root pool is not available on Windows
Uploading artifacts as "junit" to coordinator... ok
id=391207 responseStatus=201 Created token=ai37_qSK
ERROR: Job failed: exit status 1