X11 build fixups

- fixed -Werror=misleading-indentation warning
- fixed -Werror=nonnull-compare warning on xll and QT builds
- PNG_LIBPNG_VER backward compatibily changes
- giflib backward compatibily changes
- resolved some undefs for X11 build
- silenced some small compile warnings in JGE Makefile
- added -DTIXML_USE_STL to remaining build types (PSP had it added)
- fixed x11 Boost incompatibility issue part of #548
- reworked PrecompiledHeader.h platforms used

JGE/src/zipFS/zfsystem.cpp

@@ -631,8 +631,8 @@ streamoff filesystem::CentralDirZipped(std::istream & File, std::streamoff begin
     std::streamoff eof = begin + size;
 
 	// Look for the "end of central dir" header. Start minimum 22 bytes before end.
-    if (! File.seekg(eof - 22, ios::beg))
-        return -1;
+	if (! File.seekg(eof - 22, ios::beg))
+		return -1;
 
 	streamoff EndPos;
 	streamoff StartPos = File.tellg();