libwebp: update to 0.4.4

third_party/libwebp/dsp/dsp.h

Index: third_party/libwebp/dsp/dsp.h
diff --git a/third_party/libwebp/dsp/dsp.h b/third_party/libwebp/dsp/dsp.h
index 2409bae13e476ee93e840af4a365ae14aa079821..a2c3951745af87a1ae28e1a320f7b45e315d556f 100644
--- a/third_party/libwebp/dsp/dsp.h
+++ b/third_party/libwebp/dsp/dsp.h
@@ -36,14 +36,9 @@ extern "C" {
 # define LOCAL_GCC_PREREQ(maj, min) 0
 #endif
 
-#ifdef __clang__
-# define LOCAL_CLANG_VERSION ((__clang_major__ << 8) | __clang_minor__)
-# define LOCAL_CLANG_PREREQ(maj, min) \
-    (LOCAL_CLANG_VERSION >= (((maj) << 8) | (min)))
-#else
-# define LOCAL_CLANG_VERSION 0
-# define LOCAL_CLANG_PREREQ(maj, min) 0
-#endif  // __clang__
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
 
 #if defined(_MSC_VER) && _MSC_VER > 1310 && \
     (defined(_M_X64) || defined(_M_IX86))
@@ -73,7 +68,8 @@ extern "C" {
 #define WEBP_USE_NEON
 #endif
 
-#if defined(__mips__) && !defined(__mips64) && (__mips_isa_rev < 6)
+#if defined(__mips__) && !defined(__mips64) && \
+    defined(__mips_isa_rev) && (__mips_isa_rev >= 1) && (__mips_isa_rev < 6)
 #define WEBP_USE_MIPS32
 #if (__mips_isa_rev >= 2)
 #define WEBP_USE_MIPS32_R2