[Bug debug/61352] gcc 4.9.0 debug code confuses gdb 7.7.1 on darwin11/12 but not gcc 4.8.3 debug code

["howarth.at.gcc at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61352

--- Comment #3 from Jack Howarth <howarth.at.gcc at gmail dot com> ---
The problem here is that for some reason gcc 4.9.0 has stop running dsymutil as
it should on the created executablesâ

% gcc-fsf-4.8 -g -O1 himenoBMTxpa.c -v
â
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.8.5' '-g' '-O1' '-v'
'-mtune=core2'
 /sw/lib/gcc4.8/libexec/gcc/x86_64-apple-darwin12.5.0/4.8.3/collect2 -dynamic
-arch x86_64 -macosx_version_min 10.8.5 -weak_reference_mismatches non-weak -o
a.out -L/sw/lib/gcc4.8/lib/gcc/x86_64-apple-darwin12.5.0/4.8.3
-L/sw/lib/gcc4.8/lib/gcc/x86_64-apple-darwin12.5.0/4.8.3/../../..
/var/folders/1l/n78sywl52lz6kkys6nv7mnph0000gp/T//ccUNwYnw.o -no_compact_unwind
-lSystem -lgcc_ext.10.5 -lgcc -lSystem -v -idsym -dsym
collect2 version 4.8.3
/usr/bin/ld -dynamic -arch x86_64 -macosx_version_min 10.8.5
-weak_reference_mismatches non-weak -o a.out
-L/sw/lib/gcc4.8/lib/gcc/x86_64-apple-darwin12.5.0/4.8.3
-L/sw/lib/gcc4.8/lib/gcc/x86_64-apple-darwin12.5.0/4.8.3/../../..
/var/folders/1l/n78sywl52lz6kkys6nv7mnph0000gp/T//ccUNwYnw.o -no_compact_unwind
-lSystem -lgcc_ext.10.5 -lgcc -lSystem -v
@(#)PROGRAM:ld  PROJECT:ld64-236.4
configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 armv6m armv7m
armv7em
Library search paths:
    /sw/lib/gcc4.8/lib/gcc/x86_64-apple-darwin12.5.0/4.8.3
    /sw/lib/gcc4.8/lib
    /usr/lib
    /usr/local/lib
Framework search paths:
    /Library/Frameworks/
    /System/Library/Frameworks/
dsymutil a.out
%

% gcc-fsf-4.9 -g -O1 himenoBMTxpa.c -v
â
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.8.5' '-g' '-O1' '-v'
'-mtune=core2'
 /sw/lib/gcc4.9/libexec/gcc/x86_64-apple-darwin12.5.0/4.9.0/collect2 -dynamic
-arch x86_64 -macosx_version_min 10.8.5 -weak_reference_mismatches non-weak -o
a.out -L/sw/lib/gcc4.9/lib/gcc/x86_64-apple-darwin12.5.0/4.9.0
-L/sw/lib/gcc4.9/lib/gcc/x86_64-apple-darwin12.5.0/4.9.0/../../..
/var/folders/1l/n78sywl52lz6kkys6nv7mnph0000gp/T//ccvoj6eP.o -no_compact_unwind
-lSystem -lgcc_ext.10.5 -lgcc -lSystem -v -idsym -dsym
collect2 version 4.9.0
/usr/bin/ld -dynamic -arch x86_64 -macosx_version_min 10.8.5
-weak_reference_mismatches non-weak -o a.out
-L/sw/lib/gcc4.9/lib/gcc/x86_64-apple-darwin12.5.0/4.9.0
-L/sw/lib/gcc4.9/lib/gcc/x86_64-apple-darwin12.5.0/4.9.0/../../..
/var/folders/1l/n78sywl52lz6kkys6nv7mnph0000gp/T//ccvoj6eP.o -no_compact_unwind
-lSystem -lgcc_ext.10.5 -lgcc -lSystem -v
@(#)PROGRAM:ld  PROJECT:ld64-236.4
configured to support archs: armv6 armv7 armv7s arm64 i386 x86_64 armv6m armv7m
armv7em
Library search paths:
    /sw/lib/gcc4.9/lib/gcc/x86_64-apple-darwin12.5.0/4.9.0
    /sw/lib/gcc4.9/lib
    /usr/lib
    /usr/local/lib
Framework search paths:
    /Library/Frameworks/
    /System/Library/Frameworks/
 /usr/bin/nm -n /var/folders/1l/n78sywl52lz6kkys6nv7mnph0000gp/T//ccvoj6eP.o
%

I don't see any obvious changes to gcc/config/darwin.h or gcc/config/darwin9.h
to explain this regression where DSYMUTIL_SPEC, being passed on
LINK_COMMAND_SPEC, is ignored.