Allow map_file_generator to use host tools

map_file_generator need to invoke binaries such as `unsquashfs` .
These binaries are built from android source tree, so add host binary
output directory to PATH variable so that map_file_generator can use
these binaries.

Test: th
Bug: 286870582
Change-Id: I56634293ee885fc4612627578a22cdf57bc13bfc
diff --git a/core/Makefile b/core/Makefile
index 1814f98..426dded 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5894,7 +5894,9 @@
 define copy-image-and-generate-map
   mkdir -p $(2)
   cp $(1) $(2)
-  $(if $(3),$(HOST_OUT_EXECUTABLES)/map_file_generator $(1) $(2)/$(3))
+  $(if $(3),
+    UNSQUASHFS=$(HOST_OUT_EXECUTABLES)/unsquashfs $(HOST_OUT_EXECUTABLES)/map_file_generator $(1) $(2)/$(3)
+  )
 endef
 
 # By conditionally including the dependency of the target files package on the