Added Android build target

common.gypi

 {
   'variables': {
     'visibility%': 'hidden',
     'library%': 'static_library',
     'component%': '',
     'want_separate_host_toolset': 0,
   },
 
   'conditions': [
     ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
        or OS=="netbsd" or OS=="android"', {
       'target_defaults': {
         'cflags': [ '-Wall', '-W', '-Wno-unused-parameter',
                     '-Wnon-virtual-dtor', '-pthread', '-fno-rtti',
-                    '-pedantic', '-std=gnu++0x', '-fexceptions', ],

[Wladimir Palant, 2013/05/16 10:32:19]

-Wno-error flags were merely left-overs from back when we included
standalone.gypi everywhere. Adding -std=gnu++0x fixes a bunch of warnings that
we had in regular builds as well and I figured that -fexceptions won't hurt if
specified for all *ix OSes.

[Felix Dahlke, 2013/05/23 13:35:44]

We should use -std=c++0x if possible, -std=gnu++0x enables some GNU-specific
stuff we probably don't want.

Note that -std=c++0x will give us a bunch of features, like nullptr, lambdas and
variadic templates - depending on the compiler version. We should probably
define somewhere which subset of C++0x we can use, in order support slightly
older compilers. Previously, we only had access to C++0x features in the
standard library, no new language features.

+                    '-pedantic', '-std=c++0x', '-fexceptions', ],
         'ldflags': [ '-pthread', ],
       },
     }],
     ['OS=="android"', {
       'target_defaults': {
         'cflags!': [
           '-pthread',  # Not supported by Android toolchain.
         ],
         'ldflags!': [
           '-pthread',  # Not supported by Android toolchain.
         ],
       },
     }],
   ],
 
   'target_defaults': {
     'msvs_cygwin_shell': 0,
   }
 }