win32: fix libtcc support

win32: fix libtcc support

For "tcc -run file.c", I was trying to initialize the FP control
in a function in libtcc1.a (_runmain) before calling main.

Unfortunately that turned out to cause problems with for example
libtcc_test since such usage doesn't necessarily define a 'main'
function.

So for tcc -run we're back to relying on the FP control word
that is set in the startup code of tcc.exe rsp. libtcc.dll.

This fixes part of commit 73faaea227a53e365dd75f1dba7a5071c7b5e541