Strip whitespace from INTERNAL_VENDOR_RAMDISK_FRAGMENTS

aosp/1664081 introduces a bug where if BOARD_VENDOR_RAMDISK_FRAGMENTS is
empty, then INTERNAL_VENDOR_RAMDISK_FRAGMENTS would become " " (single
whitespace).
Just unconditionally $(strip ...) the variable to remove any extra
whitespace.

Bug: 183395459
Test: m dist and check *-target_files-*.zip
Change-Id: Ic842756f3a64c073593592d22c980820664e11c1
diff --git a/core/Makefile b/core/Makefile
index fc9f64e..ce52b1b 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -236,6 +236,10 @@
 )
 INTERNAL_VENDOR_RAMDISK_FRAGMENTS += $(BOARD_VENDOR_RAMDISK_FRAGMENTS)
 
+# Strip the list in case of any whitespace.
+INTERNAL_VENDOR_RAMDISK_FRAGMENTS := \
+  $(strip $(INTERNAL_VENDOR_RAMDISK_FRAGMENTS))
+
 # Assign --ramdisk_name for each vendor ramdisk fragment.
 $(foreach vendor_ramdisk_fragment,$(INTERNAL_VENDOR_RAMDISK_FRAGMENTS), \
   $(if $(filter --ramdisk_name,$(BOARD_VENDOR_RAMDISK_FRAGMENT.$(vendor_ramdisk_fragment).MKBOOTIMG_ARGS)), \