Bump version for Makefile change.

Make.inc

@@ -3,7 +3,7 @@
 OS := $(shell uname)
 # Do not forget to bump SOMINOR when changing VERSION,
 # and SOMAJOR when breaking ABI in a backward-incompatible way
-VERSION = 0.5.2
+VERSION = 0.5.3
 SOMAJOR = 2
 SOMINOR = 3
 DESTDIR =