On FreeBSD 12 sys/sysctl.h requires sys/types.h

Else build fails with:

    In file included from ExecutablePath.hsc:42:
    /usr/include/sys/sysctl.h:1062:25: error: unknown type name 'u_int'; did you mean 'int'?
     int sysctl(const int *, u_int, void *, size_t *, const void *, size_t);
			     ^~~~~
			     int
    compiling libraries/base/dist-install/build/System/Environment/ExecutablePath_hsc_make.c failed (exit code 1)

Perhaps also also other FreeBSD releases, but additional include
will no harm even if not needed.
22 jobs for master
Status Job ID Name Coverage
  Lint
canceled #210179
lint
lint-linters

canceled #210182
lint
lint-submods-branch

canceled #210180
lint
lint-testsuite

canceled #210181
lint
typecheck-testsuite

 
  Quick Build
canceled #210183
x86_64-linux
hadrian-ghc-in-ghci

 
  Build
canceled #210186
x86_64-linux
release-x86_64-linux-deb9-dwarf

canceled #210185
x86_64-linux
validate-x86_64-linux-deb9-debug

canceled #210184
x86_64-linux
validate-x86_64-linux-deb9-hadrian

 
  Full Build
canceled #210189
aarch64-linux allowed to fail
validate-aarch64-linux-deb9

canceled #210190
armv7-linux allowed to fail
validate-armv7-linux-deb9

canceled #210191
x86_64-linux
validate-i386-linux-deb9

canceled #210188
x86_64-darwin
validate-x86_64-darwin

canceled #210192
x86_64-linux
validate-x86_64-linux-deb9-integer-simple

canceled #210187
x86_64-linux
validate-x86_64-linux-deb9-unreg-hadrian

canceled #210193
x86_64-linux
validate-x86_64-linux-fedora27

canceled #210195
x86_64-windows allowed to fail
validate-x86_64-windows

canceled #210194
x86_64-windows allowed to fail
validate-x86_64-windows-hadrian

 
  Cleanup
canceled #210196
x86_64-darwin
cleanup-darwin

 
  Packaging
canceled #210197
x86_64-linux allowed to fail
doc-tarball

 
  Testing
canceled #210198
x86_64-linux allowed to fail manual
hackage

canceled #210199
x86_64-linux
perf-nofib

 
  Deploy
canceled #210200
x86_64-linux allowed to fail
pages