From original commit: Most versions of GCC are smart enough to understand when we are compiling/linking C++ code. However, the GCC 4.5 in MingW is apparently not one of the smart ones so the tr1/hash detection code fails on Windows. On the other hand, C++ changed the C prototype for ANYARGS functions, so e.g. BigDecimal C ext will not compile properly with g++. So, we provide options for both in configure.
The current build system is minimally useful and barely enables non-standard build configurations. Better support will have to wait until the build system is rebuilt.