config.gcc (*-*-linux*): Default to --enable-threads=posix if no --{enable,disable}-threads is given to...

	* config.gcc (*-*-linux*): Default to --enable-threads=posix if no
	--{enable,disable}-threads is given to configure.
	(alpha*-*-linux*, hppa*-*-linux*, i[34567]86-*-linux*,
	x86_64-*-linux*, ia64*-*-linux*, m68k-*-linux*, mips*-*-linux*,
	powerpc-*-linux-gnualtivec*, powerpc-*-linux*, s390-*-linux*,
	s390x-*-linux*, sh-*-linux*, sparc-*-linux*, sparc64-*-linux*):
	Remove thread_file setting here.

From-SVN: r56071