ANDROID: Minor fixes to build-specific makefile.

This fixes two minor issues when trying to cross-compile to Android on
Win32 using the Win32 Android SDK/NDK and MinGW shell.

However, this is still no working as DX and APKBUILDER are batch files
in the Win32 SDK (which then call the real Java tools) and these fail
to run in shell. However, using "cmd /C" also fails as the paths in the
parameters have unix, rather than native separators. Unsure how to fix.

backends/platform/android/android.mk

@@ -50,7 +50,7 @@ JAVACFLAGS = -source 1.5 -target 1.5
 
 ANDROID_JAR = $(ANDROID_SDK)/platforms/android-14/android.jar
 
-PATH_BUILD = build.tmp
+PATH_BUILD = ./build.tmp
 PATH_BUILD_ASSETS = $(PATH_BUILD)/assets
 PATH_BUILD_CLASSES_MAIN_TOP = $(PATH_BUILD)/classes.main
 PATH_BUILD_CLASSES_PLUGIN_TOP = $(PATH_BUILD)/classes.plugin
@@ -128,7 +128,7 @@ $(FILE_RESOURCES_MAIN): $(FILE_MANIFEST) $(RESOURCES) $(ANDROID_JAR) $(DIST_FILE
 	work_dir=`pwd`; \
 	for i in $(PATH_BUILD_ASSETS)/*.zip; do \
 		echo "recompress $$i"; \
-		cd $$work_dir; \
+		cd "$$work_dir"; \
 		$(RM) -rf $(PATH_BUILD_ASSETS)/tmp; \
 		$(MKDIR) $(PATH_BUILD_ASSETS)/tmp; \
 		unzip -q $$i -d $(PATH_BUILD_ASSETS)/tmp; \