Fix iphone simulator build.

external/buildscripts/build_runtime_iphone.sh

@@ -4,6 +4,7 @@ MAC_SDK_VERSION=10.6
 ASPEN_ROOT=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer
 SIMULATOR_ASPEN_ROOT=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer
 XCOMP_ASPEN_ROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX${MAC_SDK_VERSION}.sdk
+BUILDSCRIPTSDIR=external/buildscripts
 
 if [ ! -d $ASPEN_ROOT/SDKs/iPhoneOS${SDK_VERSION}.sdk ]; then
 	SDK_VERSION=5.1
@@ -148,7 +149,7 @@ build_iphone_simulator ()
 	export CC="$SIMULATOR_ASPEN_ROOT/usr/bin/gcc -arch i386"
 	export CXX="$SIMULATOR_ASPEN_ROOT/usr/bin/g++ -arch i386"
 	export LIBTOOLIZE=`which glibtoolize`
-	perl build_runtime_osx.pl -iphone_simulator=1 || exit 1
+	perl ${BUILDSCRIPTSDIR}/build_runtime_osx.pl -iphone_simulator=1 || exit 1
 	echo "Copying iPhone simulator static lib to final destination";
 	mkdir -p builds/embedruntimes/iphone
 	cp mono/mini/.libs/libmono.a builds/embedruntimes/iphone/libmono-i386.a