* libm/math/ef_sqrt.c: Delete unused variable sign.

	* libm/math/ef_sqrt.c: Delete unused variable sign.
	* libc/stdlib/getenv.c: Delete "char *_findenv_r ();", as is not a
	proper prototype, and is properly prototyped in stdlib.h, anyway.
	* libc/stdlib/getenv_r.c: Ditto.
	* libc/search/hash.c: Add _DEFUN to __hash_open() declaration; add
	#define __DBINTERFACE_PRIVATE to activate prototypes from db_local.h.
	* libc/search/db_local.h: Correct __hash_open() prototype.
	* libc/sys/linux/cmath/math_private.h:  Eliminate compiler warnings:
	Remove #define INFINITY (redefines from math.h); remove #define __isnanf
	and #define __isinff isinff.