[STRING]: Move strcasecmp/strncasecmp to lib/string.c

We have several platforms using local copies of identical
code.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/xtensa/lib/Makefile b/arch/xtensa/lib/Makefile
index ed935b5..6c4fdd8 100644
--- a/arch/xtensa/lib/Makefile
+++ b/arch/xtensa/lib/Makefile
@@ -2,6 +2,6 @@
 # Makefile for Xtensa-specific library files.
 #
 
-lib-y	+= memcopy.o memset.o checksum.o strcasecmp.o \
+lib-y	+= memcopy.o memset.o checksum.o \
 	   usercopy.o strncpy_user.o strnlen_user.o
 lib-$(CONFIG_PCI) += pci-auto.o