When glog 0.4.0 is built using musl instead of glibc, the compilation
for this test fails because musl doesn't provide execinfo.h, which sets
HAVE_STACKTRACE to false.

Tested by building glog with musl and verifying that the build succeeds
with this patch. [See https://github.com/openwrt/packages/pull/8583]
Signed-off-by: Amol Bhave <ambhave@fb.com>