Fix mismatched visibility of StgRun

From Gabor Greif:

I am getting linker errors when bootstrapping HEAD with a recent
v7.7-20130220 GHC. This is a RHEL5 system:

"inplace/bin/ghc-stage1" -package-name rts -shared -dynamic -dynload
deploy -no-auto-link-packages -Lrts/dist/build -lffi  -optl-Wl,-rpath
-optl-Wl,'$ORIGIN' `cat rts/libs.depend`
<<snip>>
rts/dist/build/AutoApply.debug_dyn_o  -o
rts/dist/build/libHSrts_debug-ghc7.7.20130402.so
/usr/bin/ld: rts/dist/build/Schedule.dyn_o: relocation R_X86_64_PC32
against `StgRun' can not be used when making a shared object;
recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
collect2: ld returned 1 exit status

From PHO:

The old binutils comes with RHEL5 fails to link a shared library if
there is a reference to a hidden symbol that isn't locally
defined. See: https://gist.github.com/phonohawk/5308015

Personally I don't think this is an old binutils' fault, because the
newer one is essentially turning an otherwise global symbol to a local
one depending on its call site, which feels rather wrong to me.

The attached patch should fix the problem anyway.

From Gabor Greif:

Thanks a lot! This worked, but now we have the libffi-related problem
on install:

/home/ggreif/lib/ghc-7.7.20130403/bin/ghc-pkg: error while loading
shared libraries: libHSterminfo-0.3.2.5-ghc7.7.20130403.so: cannot
open shared object file: No such file or directory
make[1]: *** [install_packages] Error 127

This is described in another mail thread, so I'll relax now.

My patch is to change the visibility of StgRun/StgReturn for each and every platforms, but I've only tested it on my NetBSD/amd64, Linux/x86_64 and FreeBSD/i386 boxes. I hope I've not broken other platforms namely Darwin/i386, Darwin/x86_64, Darwin/PPC32, Linux/PPC32, Linux/PPC64, Linux/ARM, iOS/ARM and Sparc.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
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