Strip -fPIC compiler flag during compilation

This is a partial revert of #9750.

The binaryen change that was designed to allow this to work was
reverted: WebAssembly/binaryen#2513

Author: sbc100

emcc.py

@@ -1937,6 +1937,9 @@ def is_link_flag(flag):
         return any(flag.startswith(x) for x in ('-l', '-L', '-Wl,'))
 
       compile_args = [a for a in newargs if a and not is_link_flag(a)]
+      if '-fPIC' in compile_args and not shared.Settings.RELOCATABLE:
+        shared.warning('ignoring -fPIC flag when not building with SIDE_MODULE or MAIN_MODULE')
+        compile_args.remove('-fPIC')
 
       # Bitcode args generation code
       def get_clang_command(input_files):

tests/test_core.py

@@ -8554,6 +8554,7 @@ def test_undefined_main(self):
 
   def test_fpic_static(self):
     self.emcc_args.append('-fPIC')
+    self.emcc_args.remove('-Werror')
     self.do_run_in_out_file_test('tests', 'core', 'test_hello_world')
 
   @node_pthreads