re PR target/47192 (m68k target - gcc uses stack frame after it has been unlinked when compiling with -Os)

	PR target/47192
	* config/m68k/m68k.c (m68k_expand_epilogue): Emit a scheduling
	barrier prior to deallocating the stack.

	PR target/47192
	* gcc.target/m68k/pr47192.c: New test.

From-SVN: r242575