Make DLEXT var configurable in programs and tests makefiles
diff --git a/programs/Makefile b/programs/Makefile
index 443689b..25f184f 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -35,7 +35,7 @@
 SHARED_SUFFIX=.$(DLEXT)
 endif
 else
-DLEXT=so
+DLEXT ?= so
 EXEXT=
 SHARED_SUFFIX=
 endif