Fix a system library build issue, where .S files would not be built with the same cmdline args as the other files. (#16417)

In particular, this would cause the .S files to not get the same preprocessor
defines as .c and .cpp files have, so customizing .S files on preprocessor
conditions was not possible.

Author: juj

tests/report_result.h

@@ -10,6 +10,8 @@
 #ifndef REPORT_RESULT_H_
 #define REPORT_RESULT_H_
 
+#ifndef __ASSEMBLER__ // Emit this file only to C/C++ language headers and not when preprocessing .S files
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -35,4 +37,6 @@ void _MaybeReportResult(int result, int sync);
   #define MAYBE_REPORT_RESULT_SYNC(result) _MaybeReportResult((result), 1)
 #endif
 
+#endif
+
 #endif // REPORT_RESULT_H_

tools/system_libs.py

@@ -290,7 +290,6 @@ def build_objects(self, build_dir):
     commands = []
     objects = []
     cflags = self.get_cflags()
-    base_flags = get_base_cflags()
     case_insensitive = is_case_insensitive(build_dir)
     for src in self.get_files():
       object_basename = shared.unsuffixed_basename(src)
@@ -310,13 +309,12 @@ def build_objects(self, build_dir):
         cmd = [shared.EMCC]
       else:
         cmd = [shared.EMXX]
+
+      cmd += cflags
       if ext in ('.s', '.S'):
-        cmd += base_flags
         # TODO(sbc) There is an llvm bug that causes a crash when `-g` is used with
         # assembly files that define wasm globals.
-        cmd.remove('-g')
-      else:
-        cmd += cflags
+        cmd = [arg for arg in cmd if arg != '-g']
       cmd = self.customize_build_cmd(cmd, src)
       commands.append(cmd + ['-c', src, '-o', o])
       objects.append(o)