Merge pull request #75 from GLVis/makefile-tweak

Update makefile [makefile-tweak]

Author: v-dobrev

makefile

@@ -49,9 +49,14 @@ GLVIS_CONFIG_MK ?=
 PREFIX ?= ./bin
 INSTALL ?= /usr/bin/install
 
-# Archiver
-AR ?= ar
-ARFLAGS ?= cruv
+# Archiver: AR and ARFLAGS are defined by default, RANLIB is not.
+# The default value of AR is 'ar' and we do not want to change that.
+# The default value of ARFLAGS is 'rv', however, we want to set a different
+# default, so we modify ARFLAGS, unless it was already changed on the command
+# line or in the configuration file $(GLVIS_CONFIG_MK).
+ifeq ($(origin ARFLAGS),default)
+   ARFLAGS = cruv
+endif
 RANLIB ?= ranlib
 
 # Use the MFEM build directory