global vars and symbol visibility for mips32/elf

[Jim Wilson]

	#include <assert.h>
	int optind[30000], optarg[30000];
	...

This is a good example.  A number of systems get this wrong.  One way to fix
this is to make -fno-common the default.  However, ANSI/ISO C does not require
this solution.  There are some other ways that this problem could be solved,
by changing how the C library works, or by changing how the linker works.
-fno-common is probably the easiest solution though.

Jim