Use wrapper headers for stdint.h instead of built-in macros

[komh]

__STDC_CONSTANT_MACROS and __STDC_LIMIT_MACROS are defined as built-in
macros. This causes unnecessary warnings of redefinition of those
macros.

Instead, use wrapper headers for them.

Here is the patch. Review, please...

0001-OS-2-Use-wrapper-headers-for-stdint.h-instead-of-bui.patch.txt

[komh]

You should add \usr\local492\lib\gcc\ix86-pc-os2-emx\4.9.2\include, where x depends on your build target, primarily 3 or 6, before \usr\include. The directory is missing in gcc4.cmd, gcc4 setup script. Modifying it woube be better.