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 73faaea227
13b997668e