Apparently some ports on arm require these symbols, and while they were
available in llvm's libunwind, they were never exported via the arm
specific Symbol.map. Put them in the same version block as gcc does
(GCC_3.5).
Reported by: Robert Clausecker <fuz_at_fuz.su>
MFC after: 3 days
In original GNU libgcc, _Unwind_Backtrace is published with GCC_3.3 version
for all architectures but ARM. For ARM should be publishes with GCC_4.3.0
version. This was originally omitted in r255095, fixed in r318024 and omitted
aging in LLVM libunwind implementation in r354347.
For ARM _Unwind_Backtrace should be published as default with GCC_4.3.0
version , (because this is right original version) and again as
normal(not-default) with GCC_3.3 version (to maintain ABI compatibility
compiled/linked with wrong pre r318024 libgcc)
PR: 233664
GCC's libgcc exports a few ARM-specific symbols for ARM EABI, AEABI, or
EHABI or whatever it's called. Export the same ones from LLVM-libunwind's
libgcc_s, on ARM. As part of this, convert libgcc_s from a direct
Version.map to one constructed from component Symbol.map files. This allows
the ARM-specific Symbol.map to be included only on ARM.
Fix ARM-only oddities in struct name/aliases in LLVM-libunwind to match
non-ARM definitions and ARM-specific expectations in libcxxrt /
libcompiler_rt.
No functional change intended for non-ARM architectures.
This commit does not actually flip the switch for ARM defaults from libgcc
to llvm-libunwind, but makes it possible (to compile, anyway).
