bitmap.c: Change NULL_PTR to NULL or "(rtx*)0".

bitmap.c: Change NULL_PTR to NULL or "(rtx*)0".

	* bitmap.c: Change NULL_PTR to NULL or "(rtx*)0".
	* c-common.c: Likewise.
	* c-decl.c: Likewise.
	* combine.c: Likewise.
	* rs6000.c: Likewise.
	* except.c: Likewise.
	* explow.c: Likewise.
	* expr.c: Likewise.
	* fold-const.c: Likewise.
	* function.c: Likewise.
	* gcc.c: Likewise.
	* gcse.c: Likewise.
	* integrate.c: Likewise.
	* loop.c: Likewise.
	* objc/objc-act.c: Likewise.
	* recog.c: Likewise.
	* reg-stack.c: Likewise.
	* reload.c: Likewise.
	* reload1.c: Likewise.
	* simplify-rtx.c: Likewise.
	* stmt.c: Likewise.
	* varasm.c: Likewise.

From-SVN: r41722