objcopy --extract-symbol testcase

Run the test for more than just ELF.  Shows that objcopy --extract-symbol
isn't working on PE, mips, mmix and some aout targets.

	* config/default.exp (size): New global.
	* ld-elf/extract-symbol-1.s,
	* ld-elf/extract-symbol-1.ld,
	* ld-elf/extract-symbol-1sec.d,
	* ld-elf/extract-symbol-1sym.d: Delete.
	* ld-scripts/script.exp (extract_symbol_test): New.