Fix file embedding tests under windows that were broken by #16050 (#16102)

Author: sbc100

.circleci/config.yml

@@ -444,7 +444,7 @@ jobs:
       # note we do *not* build all libraries and freeze the cache; as we run
       # only limited tests here, it's more efficient to build on demand
       - run-tests:
-          test_targets: "other.test_emcc_cflags other.test_stdin other.test_bad_triple core2.test_sse1 core2.test_ccall other.test_closure_externs other.test_binaryen_debug other.test_js_optimizer_parse_error other.test_output_to_nowhere other.test_emcc_dev_null other.test_cmake* other.test_system_include_paths other.test_emar_response_file core2.test_utf16 other.test_special_chars_in_arguments other.test_toolchain_profiler other.test_realpath_nodefs other.test_response_file_encoding other.test_libc_progname"
+          test_targets: "other.test_emcc_cflags other.test_stdin other.test_bad_triple core2.test_sse1 core2.test_ccall other.test_closure_externs other.test_binaryen_debug other.test_js_optimizer_parse_error other.test_output_to_nowhere other.test_emcc_dev_null other.test_cmake* other.test_system_include_paths other.test_emar_response_file core2.test_utf16 other.test_special_chars_in_arguments other.test_toolchain_profiler other.test_realpath_nodefs other.test_response_file_encoding other.test_libc_progname other.test_realpath other.test_embed_file_dup"
   test-mac:
     executor: mac
     environment:

tools/file_packager.py

@@ -134,6 +134,10 @@ def err(*args):
   print(*args, file=sys.stderr)
 
 
+def to_unix_path(p):
+  return p.replace(os.path.sep, '/')
+
+
 def base64_encode(b):
   b64 = base64.b64encode(b)
   return b64.decode('ascii')
@@ -265,18 +269,19 @@ def generate_object_file(data_files):
         err('embedding %s at %s' % (f.srcpath, f.dstpath))
 
       size = os.path.getsize(f.srcpath)
-      name = to_asm_string(f.dstpath)
+      dstpath = to_asm_string(f.dstpath)
+      srcpath = to_unix_path(f.srcpath)
       out.write(dedent(f'''
       .section .rodata.{f.c_symbol_name},"",@
 
       # The name of file
       {f.c_symbol_name}_name:
-      .asciz "{name}"
-      .size {f.c_symbol_name}_name, {len(name)+1}
+      .asciz "{dstpath}"
+      .size {f.c_symbol_name}_name, {len(dstpath)+1}
 
       # The size of the file followed by the content itself
       {f.c_symbol_name}:
-      .incbin "{f.srcpath}"
+      .incbin "{srcpath}"
       .size {f.c_symbol_name}, {size}
       '''))
 
@@ -462,7 +467,7 @@ def main():
 
   for file_ in data_files:
     # name in the filesystem, native and emulated
-    file_.dstpath = file_.dstpath.replace(os.path.sep, '/')
+    file_.dstpath = to_unix_path(file_.dstpath)
     # If user has submitted a directory name as the destination but omitted
     # the destination filename, use the filename from source file
     if file_.dstpath.endswith('/'):