Don't mix uint32_t and DWORD for TexLoad return type

MinGW fails to build it when the return type of the function pointers in the
TexLoad load_table is a mixture of uint32_t (unsigned int) and DWORD (aka long
unsigned int).
Merge pull request #4 from ecsv/ftbfs

Don't mix uint32_t and DWORD for TexLoad return type