Compile with -Wno-unused-local-typedefs to allow compilation with GCC 4.8

Compile with -Wno-unused-local-typedefs to prevent compilation with GCC 4.8 from failing. The problem is that STATIC_CHECK internally uses a typedef which is only used as check whether a condition is compile-time evaluatable. As it is not otherwise used, GCC warns about "locally defined but not used".

BUG=v8:2149

[Tobias Burnus, 2012-05-24 08:26:20]

GCC 4.8 has a new check warning: -Wunused-local-typedefs. That warning is
enabled by -Wall and due to -Werror it prevents the compilation with of v8 with
GCC 4.8.

v8's CHECK_STATIC check (in src/checks.h) uses a typedef to test whether a
condition can be evaluated at compile time or not. As the typedef is only used
for that purpose, the warning gets triggered.

As I do not see an easy way out, I suggest to simply silence the warning. An
alternative would be to find a clever replacement.

At least with GCC 4.7, the -Wno-unused-local-typedefs flag gets ignored, but I
think GCC ignores all unknown -Wno-* flags. Hence, this change should also work
with older GCCs.

Tobias

[Sven Panne, 2012-05-24 08:38:11]

As I mentioned in http://code.google.com/p/v8/issues/detail?id=2149, the right
fix is probably moving the STATIC_ASSERTS, not silencing the compiler.