scripts/rebuild.sh: Fix Darwin remote build.

This fix the Darwin remote build in two ways:

- Pass the proper target list as a parameter to the remote
  build script.

- Use proper compiler flags to ensure the build targets
  OS X 10.8. Otherwise, the i386 QEMU build fails at link
  time, due to missing __stret_sincos().

scripts/rebuild.sh

diff --git a/scripts/rebuild.sh b/scripts/rebuild.sh
index 3e1e33d..75c32ac 100755
--- a/scripts/rebuild.sh
+++ b/scripts/rebuild.sh
@@ -788,11 +788,17 @@
         if [ "$GNU_CONFIG_HOST_PREFIX" ]; then
             CROSS_PREFIX_FLAG="--cross-prefix=$GNU_CONFIG_HOST_PREFIX"
         fi
+        EXTRA_CFLAGS="-I$PREFIX/include"
+        case $1 in
+            darwin-*)
+                EXTRA_CFLAGS="$EXTRA_CFLAGS -mmacosx-version-min=10.8"
+                ;;
+        esac
         run $QEMU_ANDROID/configure \
             $CROSS_PREFIX_FLAG \
             --target-list="$QEMU_TARGET_LIST" \
             --prefix=$PREFIX \
-            --extra-cflags="-I$PREFIX/include" \
+            --extra-cflags="$EXTRA_CFLAGS" \
             --extra-ldflags="$EXTRA_LDFLAGS" \
             --disable-attr \
             --disable-blobs \
@@ -902,6 +908,7 @@
 \$PROGDIR/scripts/rebuild.sh \\
     --build-dir=/tmp/$PKG_SUFFIX/build \\
     --system=$(spaces_to_commas "$DARWIN_SYSTEMS") \\
+    --target=$(spaces_to_commas "$TARGETS") \\
     $EXTRA_FLAGS \\
     /tmp/$PKG_SUFFIX/qemu-android \\
     /tmp/$PKG_SUFFIX/aosp