Add c/dev/ppb_widget_dev.h and cpp/non_thread_safe_ref_count.h to ppapi.gyp. ...

Add c/dev/ppb_widget_dev.h and cpp/non_thread_safe_ref_count.h to ppapi.gyp.  Add a simple test to ensure all C++ files compile.  Re-sorted the includes in test_c_includes.c that uncovered a problem whereby ppapi headers expect pp_stdint.h to include stddef.h, and it wasn't doing it on Windows.

See http://codereview.chromium.org/5190004/ for an attempt at automating the test generation and verification of ppapi.gyp.

BUG=66321
TEST=None


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=66781

[dmichael(do not use this one), 2010-11-19 15:32:24]

So...  the part about updating ppapi.gyp in
http://codereview.chromium.org/5190004/ is pretty high priority.  So since I
can't seem to get my python right ;-) I split the critical part in to this CL. 
Hopefully it's small enough to get through quickly.  Our NaCl code that uses
completion callbacks can not build currently.

[David Springer, 2010-11-19 18:12:47]

LGTM.

[neb, 2010-11-19 18:16:49]

LGTM2.