add missing strcasestr checks to cmake and autotools build systems,

and update config files.

configure

@@ -19535,6 +19535,12 @@ if test "x$ac_cv_func_strncasecmp" = xyes
 then :
   printf "%s\n" "#define HAVE_STRNCASECMP 1" >>confdefs.h
 
+fi
+ac_fn_c_check_func "$LINENO" "strcasestr" "ac_cv_func_strcasestr"
+if test "x$ac_cv_func_strcasestr" = xyes
+then :
+  printf "%s\n" "#define HAVE_STRCASESTR 1" >>confdefs.h
+
 fi
 ac_fn_c_check_func "$LINENO" "vsscanf" "ac_cv_func_vsscanf"
 if test "x$ac_cv_func_vsscanf" = xyes