Fixed segfaults in programs compiled with Clang using -fobjc-nonfragile-abi on  Linux x86-32. 
Fixed segfaults in programs compiled with Clang using -fobjc-nonfragile-abi on 
Linux x86-32. 

If both -03 and -fobjc-nonfragile-abi are used, -march=i586 is required (at 
least on my Linux machine). This flag was lost during the recent GNUmakefile 
rewrite (see r35690).

In addition, I also added MinGW32 and pthread flags used previously in the 
GNUmakefile but missing in the Makefile.


git-svn-id: f6517e426f81db5247881cd92f7386583ace04fa@35794 72102866-910b-0410-8b05-ffd578937521

skudryas/gnustep-libobjc2,skudryas/gnustep-libobjc2,crontab/libobjc2,crontab/libobjc2