Fails to compile on Mac OS X 10.6

[Artem Titoulenko]

I tried to "make" it but it failed out with this:

appending configuration tag "F77" to libtool
gcc -DPACKAGE_NAME="gc" -DPACKAGE_TARNAME="gc" -DPACKAGE_VERSION="7.1" "-DPACKAGE_STRING="gc 7.1"" -DPACKAGE_BUGREPORT="[e-mail]" -DGC_VERSION_MAJOR=7 -DGC_VERSION_MINOR=1 -DPACKAGE="gc" -DVERSION="7.1" -DHAS_X86_THREAD_STATE32___EAX=1 -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 -DHAVE_STDINT_H=1 -DHAVE_UNISTD_H=1 -DHAVE_DLFCN_H=1 -DNO_EXECUTE_PERMISSION=1 -DALL_INTERIOR_POINTERS=1 -DGC_GCJ_SUPPORT=1 -DJAVA_FINALIZATION=1 -DATOMIC_UNCOLLECTABLE=1 -I./include -fexceptions -I libatomic_ops/src -g -O2 -MT mach_dep.lo -MD -MP -MF .deps/mach_dep.Tpo -c mach_dep.c -fno-common -DPIC -o .libs/mach_dep.o
In file included from mach_dep.c:163:
/usr/include/ucontext.h:42:2: error: #error ucontext routines are deprecated, and require _XOPEN_SOURCE to be defined
make[2]: *** [mach_dep.lo] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [vendor/gc/.libs/libgc.a] Error 2

I'm usually good with packages but this one is kind of a problem. Especially for kids who just git cloned it. Please fix?