VPP-221 Loosen Doxygen CLI command struct parser

Make the struct parser slighty slightly more accomodating of
whitespace in places it has no business being.

Also add missing OS_ID thing to Doxygen makefile.

Change-Id: Id3d198fd926f7a6c2ed40bc2d08907aad5d5ac33
Signed-off-by: Chris Luke <chrisy@flirble.org>
diff --git a/Makefile b/Makefile
index 5808a33..f218cb0 100644
--- a/Makefile
+++ b/Makefile
@@ -242,7 +242,7 @@
 export DOXY_DIR ?= $(WS_ROOT)/doxygen
 
 define make-doxy
-	@WS_ROOT="$(WS_ROOT)" BR="$(BR)" make -C $(DOXY_DIR) $@
+	@OS_ID="$(OS_ID)" WS_ROOT="$(WS_ROOT)" BR="$(BR)" make -C $(DOXY_DIR) $@
 endef
 
 .PHONY: bootstrap-doxygen doxygen wipe-doxygen