matrix: IGNORE_TARGET_FCM_VERSION -> VINTF_*

All "private" environment variables to assemble_vintf
(inserted by the build rules, not build system variables)
should have this prefix (to distinguish against,
e.g. PRODUCT_ENFORCE_VINTF_MANIFEST)

Test: m framework_compatibility_matrix -j

Bug: 65028233
Change-Id: Iaefa88cefc0918fb86235ea6fcd8e367cbd82788
diff --git a/compatibility_matrices/Android.mk b/compatibility_matrices/Android.mk
index 35a390a..d24d8e9 100644
--- a/compatibility_matrices/Android.mk
+++ b/compatibility_matrices/Android.mk
@@ -82,7 +82,7 @@
 $(my_gen_check_manifest): PRIVATE_SRC_FILE := $(my_manifest_src_file)
 $(my_gen_check_manifest): $(my_manifest_src_file) $(HOST_OUT_EXECUTABLES)/assemble_vintf
 	BOARD_SEPOLICY_VERS=$(BOARD_SEPOLICY_VERS) \
-	IGNORE_TARGET_FCM_VERSION=true \
+	VINTF_IGNORE_TARGET_FCM_VERSION=true \
 		$(HOST_OUT_EXECUTABLES)/assemble_vintf -i $(PRIVATE_SRC_FILE) -o $@
 
 LOCAL_GEN_FILE_DEPENDENCIES += $(my_gen_check_manifest)