Fix for test_dynamic_link_glemu (#14403)

The problem was the `GL` was being found in `system_libs_map` before
it was being looked up in `system_libs_map`.

This test was broken in #14351.  Sadly this test doesn't run under
chrome due to its use `@requires_sync_compilation`

Author: sbc100

emcc.py

@@ -3514,13 +3514,6 @@ def process_libraries(state, linker_inputs):
       new_flags.append((i, flag))
       continue
     lib = strip_prefix(flag, '-l')
-    # We don't need to resolve system libraries to absolute paths here, we can just
-    # let wasm-ld handle that.  However, we do want to map to the correct variant.
-    # For example we map `-lc` to `-lc-mt` if we are building with threading support.
-    if 'lib' + lib in system_libs_map:
-      lib = system_libs_map['lib' + lib]
-      new_flags.append((i, '-l' + strip_prefix(lib.get_base_name(), 'lib')))
-      continue
 
     logger.debug('looking for library "%s"', lib)
     js_libs, native_lib = building.map_to_js_libs(lib)
@@ -3532,6 +3525,14 @@ def process_libraries(state, linker_inputs):
         state.forced_stdlibs.append(native_lib)
       continue
 
+    # We don't need to resolve system libraries to absolute paths here, we can just
+    # let wasm-ld handle that.  However, we do want to map to the correct variant.
+    # For example we map `-lc` to `-lc-mt` if we are building with threading support.
+    if 'lib' + lib in system_libs_map:
+      lib = system_libs_map['lib' + lib]
+      new_flags.append((i, '-l' + strip_prefix(lib.get_base_name(), 'lib')))
+      continue
+
     if building.map_and_apply_to_settings(lib):
       continue