For C++ code, inttypes.h will only define PRId32 if __STDC_FORMAT_MACROS is defined (according to C99, I think). Do so in cpp/var.cc.
For C++ code, inttypes.h will only define PRId32 if __STDC_FORMAT_MACROS is
defined (according to C99, I think). Do so in cpp/var.cc.

BUG=none
TEST=builds everywhere
Review URL: http://codereview.chromium.org/3362016
lio972/ppapi,Iwan12/ppapi,thecocce/ppapi,thecocce/ppapi,humanai/ppapi,humanai/ppapi,kaijajan/ppapi,iofcas/ppapi,Iwan12/ppapi,kaijajan/ppapi,macressler/ppapi,thecocce/ppapi,lio972/ppapi,Gitzk/ppapi,Gitzk/ppapi,melchi45/ppapi,macressler/ppapi,melchi45/ppapi,humanai/ppapi,melchi45/ppapi,LinRaise/ppapi,macressler/ppapi,kaijajan/ppapi,Iwan12/ppapi,iofcas/ppapi,johnnnylm/ppapi,jmnjmn/ppapi,iofcas/ppapi,Iwan12/ppapi,jmnjmn/ppapi,kaijajan/ppapi,iofcas/ppapi,macressler/ppapi,macressler/ppapi,johnnnylm/ppapi,Gitzk/ppapi,humanai/ppapi,LinRaise/ppapi,Gitzk/ppapi,jmnjmn/ppapi,humanai/ppapi,Gitzk/ppapi,lio972/ppapi,johnnnylm/ppapi,LinRaise/ppapi,johnnnylm/ppapi,kaijajan/ppapi,LinRaise/ppapi,Iwan12/ppapi,melchi45/ppapi,thecocce/ppapi,melchi45/ppapi,iofcas/ppapi,jmnjmn/ppapi,thecocce/ppapi,lio972/ppapi,johnnnylm/ppapi,LinRaise/ppapi,jmnjmn/ppapi,lio972/ppapi