configure: Fix debugging on mingw-w64 with gdb

The relocation hack broke debugging on mingw-w64 when using gdb.  This
makes the reloc hack dependent on --disable-debug so it's still enabled
for release builds.

This is simply an immediate fix for the issue of broken debugging, we
should probably still look at the possibility of reverting it outright
if it proves to be more trouble than it's worth.  For now keeping it
enabled for release builds is a reasonable trade off.

Signed-off-by: Alex Smith <theryuu@warpsharp.info>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

configure

@@ -4634,9 +4634,9 @@ case $target_os in
         # however ld then forgets what the entry point should be (oops) so we
         # have to manually (re)set it.
         if enabled x86_32; then
-            add_ldexeflags -Wl,--pic-executable,-e,_mainCRTStartup
+            disabled debug && add_ldexeflags -Wl,--pic-executable,-e,_mainCRTStartup
         elif enabled x86_64; then
-            add_ldexeflags -Wl,--pic-executable,-e,mainCRTStartup
+            disabled debug && add_ldexeflags -Wl,--pic-executable,-e,mainCRTStartup
             check_ldflags -Wl,--high-entropy-va # binutils 2.25
             # Set image base >4GB for extra entropy with HEASLR
             add_ldexeflags -Wl,--image-base,0x140000000