Remove hardcoded -O3

Index: configure
--- configure.orig
+++ configure
@@ -21353,7 +21353,7 @@ if test "x$enable_debug" = "xyes"
 then :
   cflags_add="-g -O0"; enable_shared=no
 else $as_nop
-  cflags_add="-O3"
+  cflags_add=""
 fi
 CFLAGS="-Wall $cflags_add $CFLAGS"
 CXXFLAGS="-Wall $cflags_add $CXXFLAGS"
@@ -30660,7 +30660,7 @@ printf %s "checking for shell to use with libtool... "
         cprog=libtool_shell_test.c
         printf "%s\n" "#include <stdio.h>"                                 > $cprog
         printf "%s\n" "int main(void){printf(\"success\\n\"); return 0;}" >> $cprog
-        ltargs="--quiet --tag=CC --mode=link $CC $cprog -O3 -o $outname"
+        ltargs="--quiet --tag=CC --mode=link $CC $cprog -o $outname"
 
         # Check the shells, starting with known shells and ultimately
         # trying with 'sh' (can be any shell).
