Bump version in preparation for the upcoming release

Rules.mak

@@ -61,7 +61,7 @@ HOSTCFLAGS = -O2 -Wall
 # probably leave all this stuff alone.
 MAJOR_VERSION := 0
 MINOR_VERSION := 9
-SUBLEVEL      := 27
+SUBLEVEL      := 28
 VERSION       := $(MAJOR_VERSION).$(MINOR_VERSION).$(SUBLEVEL)
 # Ensure consistent sort order, 'gcc -print-search-dirs' behavior, etc.
 LC_ALL := C