Fix .so versioning.

Index: src/include/defaults.mk
--- src/include/defaults.mk.orig
+++ src/include/defaults.mk
@@ -65,7 +65,7 @@ SOFLAGS_CLANG =
 SOFLAGS ?=
 override _SOFLAGS := $(SOFLAGS)
 override SOFLAGS = $(_SOFLAGS) \
-		   -shared -Wl,-soname,$@.1 \
+		   -shared -Wl,-soname,$@.$(LIB$(subst lib,,$(@:%.so=%))_VERSION) \
 		   -Wl,--version-script=$(MAP) \
 		   $(call family,SOFLAGS)