rs6000: Remove a few needless 'lp64' contraints.

rs6000: Remove a few needless 'lp64' contraints.

A few tests need not be restricted to 'lp64', so remove the restriction.

A few of those need a simple change to the DejaGnu directives to suppress
'-mcmodel' flags for '-m32'.

2022-05-13  Paul A. Clarke  <pc@us.ibm.com>

gcc/testsuite
	* g++.target/powerpc/pr65240-1.C: Adjust DejaGnu directives.
	* g++.target/powerpc/pr65240-2.C: Likewise.
	* g++.target/powerpc/pr65240-3.C: Likewise.
	* g++.target/powerpc/pr65240-4.C: Likewise.
	* g++.target/powerpc/pr65242.C: Likewise.
	* g++.target/powerpc/pr67211.C: Likewise.
	* g++.target/powerpc/pr69667.C: Likewise.
	* g++.target/powerpc/pr71294.C: Likewise.