Patch attempting to build OSX TinyCC.

Patch attempting to build OSX TinyCC.

Applied patch found on stackoverflow (link below). I also found some
related changes that looked like logically needed. The stackoverflow
changes addressed only two registers which were breaking a compile.
However reading the code in the same file shows two other register
accesses that, while not breaking the build, should have the same fix.

http://stackoverflow.com/questions/3712902/problems-compiling-tcc-on-os-x/3713144#3713144

The test driver was changed by changing 'cp -u' into 'cp' as '-u' is not
supported on mac osx.

I found that osx build required the WITHOUT_LIBTCC define. I suspect the
reason for this is tcc unability to handle mach-o files. In order to
properly address this I had to change 'configure' to propagate target os
name to Makefile.

Current state is that simple tests work, but not the whole 'make test'
suite runs.

To the best of my knowledge, these changes should not impact other
platforms.