Fix version detection to work with older gmakes

Author: LourensVeen

support/shared/version.mk

@@ -1,7 +1,8 @@
 AMUSE_VERSION := $(patsubst v%,%,$(shell git describe --tags))
 
 ifeq (,$(AMUSE_VERSION))
-    AMUSE_VERSION := $(shell grep -v '^#' ../../VERSION)
+    H := #
+    AMUSE_VERSION := $(shell grep -v '^$H' ../../VERSION)
 endif
 
 export AMUSE_VERSION