Improvements to GYP build

This updates the GYP build for the processor component (on windows).
- adds/removes references to files which were added or removed from the
  repository
- includes build/common.gypi in the gyp files: needed to correctly
  detect the OS (I think, the generated MSVC solutions were broken
  without it)
- conditionally compiles code platform-specific code for the given
  platform

After this minidump processor nearly compiles with VS2013: the generated
project is correct, but some files still have compilation errors.

Disclaimer: I have not tested the GYP changes on non-windows platform,
as there does not seem to be anyone using it there.

BUG=
R=mark@chromium.org

Review URL: https://codereview.chromium.org/1643633004 .

src/common/common.gyp

@@ -35,6 +35,11 @@
       ['OS=="linux"', {
         'defines': ['HAVE_A_OUT_H'],
       }],
+      ['OS!="android"', {'sources/': [['exclude', '(^|/)android/']]}],
+      ['OS!="linux"', {'sources/': [['exclude', '(^|/)linux/']]}],
+      ['OS!="mac"', {'sources/': [['exclude', '(^|/)mac/']]}],
+      ['OS!="solaris"', {'sources/': [['exclude', '(^|/)solaris/']]}],
+      ['OS!="win"', {'sources/': [['exclude', '(^|/)windows/']]}],
     ],
   },
   'targets': [