Change index() and rindex() to a weak alias.

This allows people to still write statically linked applications that
call strchr() or strrchr() and have a local variable or function called
index.

Discussed with:	bde@

lib/libc/i386/string/strchr.S

@@ -63,6 +63,6 @@ L2:
 	ret
 END(strchr)
 
-STRONG_ALIAS(index, strchr)
+WEAK_ALIAS(index, strchr)
 
 	.section .note.GNU-stack,"",%progbits

lib/libc/i386/string/strrchr.S

@@ -64,6 +64,6 @@ L2:
 	ret
 END(strrchr)
 
-STRONG_ALIAS(rindex, strrchr)
+WEAK_ALIAS(rindex, strrchr)
 
 	.section .note.GNU-stack,"",%progbits

lib/libc/mips/string/strchr.S

@@ -58,4 +58,4 @@ fnd:
 	j		ra
 END(strchr)
 
-STRONG_ALIAS(index, strchr)
+WEAK_ALIAS(index, strchr)

lib/libc/mips/string/strrchr.S

@@ -56,4 +56,4 @@ LEAF(strrchr)
 	j		ra
 END(strrchr)
 
-STRONG_ALIAS(rindex, strrchr)
+WEAK_ALIAS(rindex, strrchr)

lib/libc/string/strchr.c

@@ -51,4 +51,4 @@ strchr(const char *p, int ch)
 	/* NOTREACHED */
 }
 
-__strong_reference(strchr, index);
+__weak_reference(strchr, index);

lib/libc/string/strrchr.c

@@ -52,4 +52,4 @@ strrchr(const char *p, int ch)
 	/* NOTREACHED */
 }
 
-__strong_reference(strrchr, rindex);
+__weak_reference(strrchr, rindex);