Rename abort JS helper function

Also, remove the comment which I believe is not longer relevant with
this change.

src/library.js

@@ -398,11 +398,7 @@ addToLibrary({
   // ==========================================================================
 
 #if !STANDALONE_WASM
-  // TODO: There are currently two abort() functions that get imported to asm
-  // module scope: the built-in runtime function abort(), and this library
-  // function _abort(). Remove one of these, importing two functions for the
-  // same purpose is wasteful.
-  abort: () => {
+  _abort_js: () => {
 #if ASSERTIONS
     abort('native code called abort()');
 #else

system/lib/libc/musl/src/exit/abort.c

@@ -6,8 +6,15 @@
 #include "lock.h"
 #include "ksigaction.h"
 
+#if __EMSCRIPTEN__
+_Noreturn void _abort_js();
+#endif
+
 _Noreturn void abort(void)
 {
+#if __EMSCRIPTEN__
+	_abort_js();
+#else
 	raise(SIGABRT);
 
 	/* If there was a SIGABRT handler installed and it returned, or if
@@ -27,4 +34,5 @@ _Noreturn void abort(void)
 	a_crash();
 	raise(SIGKILL);
 	_Exit(127);
+#endif
 }

tools/system_libs.py

@@ -1241,7 +1241,7 @@ def get_files(self):
 
     libc_files += files_in_path(
         path='system/lib/libc/musl/src/exit',
-        filenames=['_Exit.c', 'atexit.c', 'at_quick_exit.c', 'quick_exit.c'])
+        filenames=['abort.c', '_Exit.c', 'atexit.c', 'at_quick_exit.c', 'quick_exit.c'])
 
     libc_files += files_in_path(
         path='system/lib/libc/musl/src/ldso',