Display SDL configuration error, idea by Ben Taylor.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3070 c046a42c-6fe2-441c-8c8c-71466251a162

configure

@@ -553,7 +553,7 @@ cat > $TMPC << EOF
 int main( void ) { return SDL_Init (SDL_INIT_VIDEO); }
 EOF
 
-if $cc -o $TMPE `$sdl_config --cflags 2> /dev/null` $TMPC `$sdl_config --libs 2> /dev/null` 2> /dev/null ; then
+if $cc -o $TMPE `$sdl_config --cflags 2> /dev/null` $TMPC `$sdl_config --libs 2> /dev/null` 2> /tmp/qemu-$$-sdl-config.log ; then
 _sdlversion=`$sdl_config --version | sed 's/[^0-9]//g'`
 if test "$_sdlversion" -lt 121 ; then
 sdl_too_old=yes
@@ -688,6 +688,11 @@ echo "uname -r          $uname_release"
 if test $sdl_too_old = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
 fi
+if [ -s /tmp/qemu-$$-sdl-config.log ]; then
+  echo "The error log from compiling the libSDL test is: "
+  cat /tmp/qemu-$$-sdl-config.log
+fi
+rm -f /tmp/qemu-$$-sdl-config.log
 #if test "$sdl_static" = "no"; then
 #  echo "WARNING: cannot compile statically with SDL - qemu-fast won't have a graphical output"
 #fi