re PR c++/38228 (ICE with invalid use of bound member function)

    gcc/cp/ChangeLog:
    	PR c++/38228
    	* pt.c (unify): Do not allow the result of a template argument
    	deduction to be a METHOD_TYPE.
    	* cvt.c (cp_convert): Report a meaningful error for non-valid use
    	of pointer to member functions during conversions.
    	* call.c (build_new_op): Report a meaningful error for non-valid
    	use of pointer to member functions in binary expressions.
    	* typeck.c (invalid_nonstatic_memfn_p): Do not crash when EXPR is
    	NULL;
    
    gcc/testsuite/ChangeLog:
    	PR c++/38228
    	* g++.dg/expr/bound-mem-fun.C: New test.

From-SVN: r146646