Fix parallel check//% rule in gdb for non-VPATH build.

Fix parallel check//% rule in gdb for non-VPATH build.

gdb/:
	* gdb/Makefile.in (check//%): Parse 'config.status --version'
	output to recreate the configuration from the testsuite directory,
	rather than running 'config.status --recheck' from a different
	build directory.  Let configure do the recursion rather than
	doing it manually.