fix regression from #5299 : _atexit (with underscore) is implemented in our js library, and we should not also include the musl C version

Author: kripken

tests/test_other.py

@@ -5547,6 +5547,15 @@ def test_module_onexit(self):
     Popen([PYTHON, EMCC, 'src.cpp']).communicate()
     self.assertContained('exiting now, status 14', run_js('a.out.js', assert_returncode=14))
 
+  def test_underscore_exit(self):
+    open('src.cpp', 'w').write(r'''
+#include <unistd.h>
+int main() {
+  _exit(0); // should not end up in an infinite loop with non-underscore exit
+}    ''')
+    subprocess.check_call([PYTHON, EMCC, 'src.cpp'])
+    self.assertContained('', run_js('a.out.js', assert_returncode=0))
+
   def test_file_packager_huge(self):
     open('huge.dat', 'w').write('a'*(1024*1024*257))
     open('tiny.dat', 'w').write('a')

tools/system_libs.py

@@ -98,7 +98,7 @@ def create_libc(libname):
     musl_srcdir = shared.path_from_root('system', 'lib', 'libc', 'musl', 'src')
     blacklist = set(
       ['ipc', 'passwd', 'thread', 'signal', 'sched', 'ipc', 'time', 'linux', 'aio', 'exit', 'legacy', 'mq', 'process', 'search', 'setjmp', 'env', 'ldso', 'conf'] + # musl modules
-      ['memcpy.c', 'memset.c', 'memmove.c', 'getaddrinfo.c', 'getnameinfo.c', 'inet_addr.c', 'res_query.c', 'gai_strerror.c', 'proto.c', 'gethostbyaddr.c', 'gethostbyaddr_r.c', 'gethostbyname.c', 'gethostbyname2_r.c', 'gethostbyname_r.c', 'gethostbyname2.c', 'usleep.c', 'alarm.c', 'syscall.c'] + # individual files
+      ['memcpy.c', 'memset.c', 'memmove.c', 'getaddrinfo.c', 'getnameinfo.c', 'inet_addr.c', 'res_query.c', 'gai_strerror.c', 'proto.c', 'gethostbyaddr.c', 'gethostbyaddr_r.c', 'gethostbyname.c', 'gethostbyname2_r.c', 'gethostbyname_r.c', 'gethostbyname2.c', 'usleep.c', 'alarm.c', 'syscall.c', '_exit.c'] + # individual files
       ['abs.c', 'cos.c', 'cosf.c', 'cosl.c', 'sin.c', 'sinf.c', 'sinl.c', 'tan.c', 'tanf.c', 'tanl.c', 'acos.c', 'acosf.c', 'acosl.c', 'asin.c', 'asinf.c', 'asinl.c', 'atan.c', 'atanf.c', 'atanl.c', 'atan2.c', 'atan2f.c', 'atan2l.c', 'exp.c', 'expf.c', 'expl.c', 'log.c', 'logf.c', 'logl.c', 'sqrt.c', 'sqrtf.c', 'sqrtl.c', 'fabs.c', 'fabsf.c', 'fabsl.c', 'ceil.c', 'ceilf.c', 'ceill.c', 'floor.c', 'floorf.c', 'floorl.c', 'pow.c', 'powf.c', 'powl.c', 'round.c', 'roundf.c'] # individual math files
     )
     # TODO: consider using more math code from musl, doing so makes box2d faster