Update attributes to match gclibc's ansidecl.h

To ease use of WebRTC in other codebases, update some macros
to match glibc's ansidecl.h, which uses double-underscores for attributes.

NOTRY=True

Review URL: https://codereview.webrtc.org/1571653002

Cr-Commit-Position: refs/heads/master@{#11185}
diff --git a/webrtc/base/common.h b/webrtc/base/common.h
index 2086754..1b1dac6 100644
--- a/webrtc/base/common.h
+++ b/webrtc/base/common.h
@@ -178,7 +178,7 @@
 
 // Forces compiler to inline, even against its better judgement. Use wisely.
 #if defined(__GNUC__)
-#define FORCE_INLINE __attribute__((always_inline))
+#define FORCE_INLINE __attribute__ ((__always_inline__))
 #elif defined(WEBRTC_WIN)
 #define FORCE_INLINE __forceinline
 #else
@@ -193,7 +193,7 @@
 // libjingle are merged.
 #if !defined(WARN_UNUSED_RESULT)
 #if defined(__GNUC__) || defined(__clang__)
-#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#define WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
 #else
 #define WARN_UNUSED_RESULT
 #endif
diff --git a/webrtc/base/criticalsection.h b/webrtc/base/criticalsection.h
index ddbf857..5b3eaf5 100644
--- a/webrtc/base/criticalsection.h
+++ b/webrtc/base/criticalsection.h
@@ -89,7 +89,7 @@
 #if defined(WEBRTC_WIN)
   _Check_return_ bool locked() const;
 #else
-  bool locked() const __attribute__((warn_unused_result));
+  bool locked() const __attribute__ ((__warn_unused_result__));
 #endif
  private:
   CriticalSection* const cs_;
diff --git a/webrtc/base/deprecation.h b/webrtc/base/deprecation.h
index 459b898..ce950f9 100644
--- a/webrtc/base/deprecation.h
+++ b/webrtc/base/deprecation.h
@@ -37,7 +37,7 @@
 // (https://bugs.chromium.org/p/webrtc/issues/detail?id=5368).
 #define RTC_DEPRECATED __declspec(deprecated)
 #elif defined(__GNUC__)
-#define RTC_DEPRECATED __attribute__((deprecated))
+#define RTC_DEPRECATED __attribute__ ((__deprecated__))
 #else
 #define RTC_DEPRECATED
 #endif
diff --git a/webrtc/typedefs.h b/webrtc/typedefs.h
index f3839c7..6a3f441 100644
--- a/webrtc/typedefs.h
+++ b/webrtc/typedefs.h
@@ -73,7 +73,7 @@
 // libjingle are merged.
 #if !defined(WARN_UNUSED_RESULT)
 #if defined(__GNUC__) || defined(__clang__)
-#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#define WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
 #else
 #define WARN_UNUSED_RESULT
 #endif
@@ -84,7 +84,7 @@
 //   assert(result == 17);
 #ifndef ATTRIBUTE_UNUSED
 #if defined(__GNUC__) || defined(__clang__)
-#define ATTRIBUTE_UNUSED __attribute__((unused))
+#define ATTRIBUTE_UNUSED __attribute__ ((__unused__))
 #else
 #define ATTRIBUTE_UNUSED
 #endif
@@ -104,7 +104,7 @@
 #if defined(_MSC_VER)
 #define NO_RETURN __declspec(noreturn)
 #elif defined(__GNUC__)
-#define NO_RETURN __attribute__((noreturn))
+#define NO_RETURN __attribute__ ((__noreturn__))
 #else
 #define NO_RETURN
 #endif