[Bug sanitizer/69147] [5 Regression] Several hundred asan failures with 5.3.1 on x86_64-apple-darwin15

["dominiq at lps dot ens.fr" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69147

--- Comment #12 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Upstream ASan already has the fix, attaching adapted cherry-picked commit.
> Could you try it?

Bootstrapping with this patch fails with

...
 ../../../../5_work/libsanitizer/asan/asan_mac.cc
libtool: compile:  /opt/gcc/5_build/./gcc/xgcc -shared-libgcc
-B/opt/gcc/5_build/./gcc -nostdinc++
-L/opt/gcc/5_build/x86_64-apple-darwin15.2.0/libstdc++-v3/src
-L/opt/gcc/5_build/x86_64-apple-darwin15.2.0/libstdc++-v3/src/.libs
-L/opt/gcc/5_build/x86_64-apple-darwin15.2.0/libstdc++-v3/libsupc++/.libs
-B/opt/gcc/gcc5wr/x86_64-apple-darwin15.2.0/bin/
-B/opt/gcc/gcc5wr/x86_64-apple-darwin15.2.0/lib/ -isystem
/opt/gcc/gcc5wr/x86_64-apple-darwin15.2.0/include -isystem
/opt/gcc/gcc5wr/x86_64-apple-darwin15.2.0/sys-include -D_GNU_SOURCE -D_DEBUG
-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
-DASAN_HAS_EXCEPTIONS=1 -DASAN_FLEXIBLE_MAPPING_AND_OFFSET=0
-DASAN_NEEDS_SEGV=1 -DMAC_INTERPOSE_FUNCTIONS -DMISSING_BLOCKS_SUPPORT -I.
-I../../../../5_work/libsanitizer/asan -I.. -I
../../../../5_work/libsanitizer/include -I ../../../../5_work/libsanitizer
-Wall -W -Wno-unused-parameter -Wwrite-strings -pedantic -Wno-long-long -fPIC
-fno-builtin -fno-exceptions -fno-rtti -fomit-frame-pointer -funwind-tables
-fvisibility=hidden -Wno-variadic-macros -fno-ipa-icf
-I../../libstdc++-v3/include
-I../../libstdc++-v3/include/x86_64-apple-darwin15.2.0
-I../../../../5_work/libsanitizer/../libstdc++-v3/libsupc++ -std=gnu++11 -g -O2
-MT asan_mac.lo -MD -MP -MF .deps/asan_mac.Tpo -c
../../../../5_work/libsanitizer/asan/asan_mac.cc  -fno-common -DPIC -o
.libs/asan_mac.o
../../../../5_work/libsanitizer/asan/asan_mac.cc: In function 'void
__asan::MaybeReexec()':
../../../../5_work/libsanitizer/asan/asan_mac.cc:132:68: error: 'dylib_name'
was not declared in this scope
       dyld_insert_libraries && REAL(strstr)(dyld_insert_libraries,
dylib_name);
                                                                    ^
...