Enabled log formatting warnings.

[ Merge of http://go/wvgerrit/105025 ]

Clang and GCC allow for warnings against the arguments for printf-like
functions (e.i. LOGx).  These validate that the format type specified
in the format string match the corresponding argument type.

Most of the time, format specifer errors are benign; hence why they
haven't been seen as an error so far.  However, with the enabling of
specifier warnings and the enabling of warnings as errors on certain
platforms, these existing errors need to be addressed.

This CL enables format specifier warnings for most of the Widevine
code, with the OEMCrypto L3 implementation which has a single error
which requires a fix in the haystack code before being fixed in the
Widevine branch.

Strict format string warnings are not enabled for non-LP64 systems.

Bug: 137583127
Test: Compiled for Linux and Android
Change-Id: I051398332d31a20457b86563a90ad8f6d428445f

libwvdrmengine/cdm/util/include/log.h

@@ -33,8 +33,18 @@ extern LogPriority g_cutoff;
 // unit tests.
 CORE_UTIL_EXPORT void InitLogging();
 
+// Only enable format specifier warnings on LP64 systems.  There is
+// no easy portable method to handle format specifiers for int64_t.
+#if (defined(__gnuc__) || defined(__clang__)) && defined(__LP64__)
+[[gnu::format(printf, 5, 6)]] CORE_UTIL_EXPORT void Log(const char* file,
+                                                        const char* function,
+                                                        int line,
+                                                        LogPriority level,
+                                                        const char* fmt, ...);
+#else
 CORE_UTIL_EXPORT void Log(const char* file, const char* function, int line,
                           LogPriority level, const char* fmt, ...);
+#endif
 
 // Log APIs
 #ifndef LOGE