string: Cosmetic cleanup of string functions

Clean up string functions that do not have a version in gnulib on
the assumption that glibc is the canonical upstream copy of this
code. basename has a copy in gnulib but it is largely written to
handle Windows paths so merging it is not really viable. The changes
mostly consist of switching to ANSI function prototypes and removing
unused includes.

As many of these functions do not get built in a typical build due
to architecture optimized versions being used instead I built these
by hand to verify there were no build warnings and the code was
identical.

2014-04-07  Will Newton  <will.newton@linaro.org>

	* string/basename.c [HAVE_CONFIG_H]: Remove #ifdef and
	and contents.  [!_LIBC] Remove #ifndef and contents.
	(basename): Use ANSI prototype.  [_LIBC] Remove #idef.
	* string/memccpy.c (__memccpy): Use ANSI prototype.
	* string/memfrob.c (memfrob): Likewise.
	* string/strcoll.c (STRCOLL): Likewise.
	* string/strlen.c (strlen): Likewise.
	* string/strtok.c (STRTOK): Likewise.
	* string/strcat.c: Remove unused #include of memcopy.h.
	(strcat): Use ANSI prototype.
	* string/strchr.c: Remove unused #include of memcopy.h.
	(strchr): Use ANSI prototype.
	* string/strcmp.c: Remove unused #include of memcopy.h.
	(strcmp): Use ANSI prototype.
	* string/strcpy.c: Remove unused #include of memcopy.h.
	(strcpy): Use ANSI prototype.