cares-compilers.m4: remove -Wstrict-aliasing=3 from clang

Currently it is unknown if there is any version of clang that
actually supports -Wstrict-aliasing. What is known is that there
are several that don't support it.

m4/cares-compilers.m4

@@ -15,7 +15,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 71
+# serial 72
 
 
 dnl CARES_CHECK_COMPILER
@@ -851,8 +851,6 @@ AC_DEFUN([CARES_SET_COMPILER_WARNING_OPTS], [
       CLANG)
         #
         if test "$want_warnings" = "yes"; then
-          dnl All versions of clang support the same warnings as at least
-          dnl gcc 4.2.1 except -Wunused.
           tmp_CFLAGS="$tmp_CFLAGS -pedantic"
           tmp_CFLAGS="$tmp_CFLAGS -Wall -Wextra"
           tmp_CFLAGS="$tmp_CFLAGS -Wpointer-arith -Wwrite-strings"
@@ -870,7 +868,6 @@ AC_DEFUN([CARES_SET_COMPILER_WARNING_OPTS], [
           tmp_CFLAGS="$tmp_CFLAGS -Wcast-align"
           tmp_CFLAGS="$tmp_CFLAGS -Wno-system-headers"
           tmp_CFLAGS="$tmp_CFLAGS -Wshorten-64-to-32"
-          tmp_CFLAGS="$tmp_CFLAGS -Wstrict-aliasing=3"
           #
           dnl Only clang 1.1 or later
           if test "$compiler_num" -ge "101"; then