shrink-wrap: Testcases for separate shrink-wrapping

shrink-wrap: Testcases for separate shrink-wrapping

A few testcases for separate shrink-wrapping: test whether it works in a
trivial case; whether it creates more than one prologue where that is
useful; whether it puts prologues inside a loop if that is cheaper.

gcc/testsuite/
	* gcc.target/powerpc/shrink-wrap-separate-0.c: New testcase.
	* gcc.target/powerpc/shrink-wrap-separate-1.c: New testcase.
	* gcc.target/powerpc/shrink-wrap-separate-2.c: New testcase.

From-SVN: r241066