cris: support -fstack-usage

cris: support -fstack-usage

All the bits were there, used with a pre-existing
-mmax-stackframe=SIZE which unfortunately seems to lack
test-cases.

Note that the early-return for -mno-prologue-epilogue (what
some targets call -mnaked) is deliberately not clearing
current_function_static_stack_size, as I consider that
erroneous usage but don't really care to emit a better error
message.

For stack-usage-1.c, like most ILP32 targets, CRIS (at -O0)
needs 4 bytes for the return-address.  The default size of
256 seems ill chosen but not worth fixing.

gcc:
	* config/cris/cris.c (cris_expand_prologue): Set
	current_function_static_stack_size, if flag_stack_usage_info.

gcc/testsuite:
	* gcc.dg/stack-usage-1.c: Adjust for CRIS.