darwintrace.c fails to compile with gcc-4.0

[pixilla (Bradley Giesbrecht)]

$ make
...
===> making all in src/darwintracelib1.0
gcc -g -O2 -std=c99 -Wextra -Wall   -fPIC -Wno-deprecated-declarations -DHAVE_CONFIG_H -I.. -I.  -I"/usr/include"  -c -o darwintrace.o darwintrace.c
darwintrace.c:507:2: error: #error Please build with gcc-4.2 or later
darwintrace.c: In function '__darwintrace_get_filemap':
darwintrace.c:524: warning: implicit declaration of function '__sync_bool_compare_and_swap'
make[2]: *** [darwintrace.o] Error 1
...

[jeremyhu (Jeremy Huddleston Sequoia)]

Yeah, that should be updated to use OSAtomics.

[neverpanic (Clemens Lang)]

This uses OSAtomics now – but it'll likely still not compile on systems that still use gcc 4.0 (which should not be an issue, because configure probably disables it on these platforms).