configure: Do not omit frame pointers for msvc/icl debug builds

Because O1 or O2 are required to build libav with msvc/icl, this must be
explicitly set instead of just omitting Oy.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

configure

@@ -3956,6 +3956,7 @@ elif enabled pathscale; then
     add_cflags -fstrict-overflow -OPT:wrap_around_unsafe_opt=OFF
 elif enabled_any msvc icl; then
     enabled x86_32 && disable aligned_stack
+    enabled_all x86_32 debug && add_cflags -Oy-
     if enabled icl; then
         # basically -fstrict-aliasing that does not work (correctly) on icl 13.x
         check_cpp_condition "windows.h" "__ICL < 1300" && add_cflags -Qansi-alias