Fix pre-extracted PDKs

The PDK unzip logic does not place all the files in the same directory
it would place a zipfile, but instead inside a directory of the same
name:

  a/b/platform.zip!pdk.mk

turns into:

  a/b/platform/pdk.mk

So fix the PDK_FUISON_PLATFORM_DIR autodetection to take this into
account. Also don't create touch rules for the pre-extracted java files.

Bug: 118776469
Test: try building the PDK with PDK_FUSION_PLATFORM_ZIP set, and files extracted
Change-Id: Ib27d12aba773a5e6bd41fcbe8945a0bc31b8c281
diff --git a/core/pdk_fusion_modules.mk b/core/pdk_fusion_modules.mk
index 9aabd0f..235acf9 100644
--- a/core/pdk_fusion_modules.mk
+++ b/core/pdk_fusion_modules.mk
@@ -37,12 +37,14 @@
 
 # The source prebuilts are extracted in the rule of _pdk_fusion_stamp.
 # Use a touch rule to establish the dependency.
+ifndef PDK_FUSION_PLATFORM_DIR
 $(3) $(11) : $(_pdk_fusion_stamp)
 	$(hide) if [ ! -f $$@ ]; then \
 	  echo 'Error: $$@ does not exist. Check your platform.zip.' 1>&2; \
 	  exit 1; \
 	fi
 	$(hide) touch $$@
+endif
 endef
 
 # We don't have a LOCAL_PATH for the auto-generated modules, so let it be the $(BUILD_SYSTEM).