Add a macro to insert the necessary compiler/linker magic to add a
copy of an existing symbol to an older version. Also, update
check-exports.sh to be able to check for such symbols by listed them
commented-out in the appropriate section.
[thaller@redhat.com: patch modified]
Related: https://bugzilla.gnome.org/show_bug.cgi?id=742993
On ppc64, `nm` reports the exported symbols as 'D' instead of 'T'.
This caused `make check` to fail.
"D" The symbol is in the initialized data section.
"T" The symbol is in the text (code) section.
The current check caught stuff in the .ver file that was outdated, but
didn't quite get stuff that was supposed to be exported but wasn't,
in some cases. Update the regex to ensure that symbols that are
not exported, but that start with "nm_" (and aren't GObject
boilerplate) get flagged during the check.
Update internal code to return to a previous pattern of treating symbols
that start with "_" internal, and expecting symbols that start with
"nm_" to be exported.
Also fixes cases where random glibc symbols would get flagged:
00040ff4 l O *ABS* 00000000 .hidden _GLOBAL_OFFSET_TABLE_
00041380 l O .data 00000000 .hidden __dso_handle
000406e8 l O .dtors 00000000 .hidden __DTOR_END__
0000fbe4 l F .text 00000000 .hidden __i686.get_pc_thunk.cx
0002f980 l F .text 00000014 .hidden __stack_chk_fail_local
0000b1e7 l F .text 00000000 .hidden __i686.get_pc_thunk.bx
00040e60 l O *ABS* 00000000 .hidden _DYNAMIC
