apply clang-format

(Debian clang-format version 19.1.7 (3+build4)) with `--style=Google`.

Manual changes:
* clang-format disabled around macros with stringification (mostly
  assembly)
* some inline assembly strings were adjusted to avoid awkward line
  breaks
* trailing commas, `//` or suffixes (`ull`) added to help array
  formatting
* thread_utils.c: parameter comments were changed to the more common
  /*...=*/ style to improve formatting

The automatically generated code under swig/ was skipped.

Bug: 433996651
Change-Id: Iea3f24160d78d2a2653971cdf13fa932e47ff1b3

imageio/metadata.h

@@ -43,7 +43,7 @@ int MetadataCopy(const char* metadata, size_t metadata_len,
                  MetadataPayload* const payload);
 
 #ifdef __cplusplus
-}    // extern "C"
+}  // extern "C"
 #endif
 
 #endif  // WEBP_IMAGEIO_METADATA_H_