* libraries/clib/native/Math.c:
	(pow) renamed to (pow0).
	* libraries/javalib/java/lang/Math.java:
	(pow) return NaN if abs(a) is 1.0 and b is infinite. i368-linux
	glibc 2.2.4 doesn't do it.
	(pow0) new native method.
	* libraries/clib/native/String.c:
	(java_lang_String_indexOf) throw NullPointerException if pattern
	is NULL.
	* libraries/javalib/java/lang/StringBuffer.java:
	(checkIndex) new method.
	(checkExistingIndex) new method.
	(deleteCharAt) use checkExistingIndex instead of inlined check.
	(insert) use checkIndex instead of inlined check.
	(setCharAt) same.