Additional fixes for clang.

"make test" still fails for clang with these kinds or errors:
```
1/11 Testing: gxConfiguration.cxx
1/11 Test: gxConfiguration.cxx
Command: "/Users/mmoll/src/repos/gccxml/build/clang/bin/gccxml" "-I/Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/GXFront" "-I/Users/mmoll/src/repos/gccxml/build/clang/GCC_XML" "-I/Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/GXFront" "-I/Users/mmoll/src/repos/gccxml/GCC_XML/GXFront" "/Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxConfiguration.cxx" "-fxml=gxConfiguration.cxx.gcc.xml"
Directory: /Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/Testing
"gxConfiguration.cxx" start time: Apr 12 09:33 CDT
Output:
----------------------------------------------------------
In file included from /usr/include/c++/4.2.1/bits/postypes.h:49,
                 from /usr/include/c++/4.2.1/iosfwd:49,
                 from /Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/gxsys/ios/iosfwd:23,
                 from /Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/gxsys/SystemTools.hxx:15,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxSystemTools.h:22,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxConfiguration.h:20,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxConfiguration.cxx:17:
/usr/bin/../lib/clang/4.2/include/stdint.h:32:54: error: missing binary operator before token "("
In file included from /usr/include/c++/4.2.1/climits:50,
                 from /usr/include/c++/4.2.1/bits/stl_algobase.h:67,
                 from /usr/include/c++/4.2.1/bits/char_traits.h:46,
                 from /usr/include/c++/4.2.1/string:47,
                 from /Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/gxsys/stl/string:36,
                 from /Users/mmoll/src/repos/gccxml/build/clang/GCC_XML/gxsys/SystemTools.hxx:16,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxSystemTools.h:22,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxConfiguration.h:20,
                 from /Users/mmoll/src/repos/gccxml/GCC_XML/GXFront/gxConfiguration.cxx:17:
/usr/bin/../lib/clang/4.2/include/limits.h:37:54: error: missing binary operator before token "("
<end of output>
```