unicode: build maketables during build, take 2

The "all:" target is the default for running gomake
by hand, but it is not used during the build.
The build runs make install and make test.

Save the build of maketables for the test phase
so that the packages it needs will have been
installed already.

R=r, r2
CC=golang-dev
https://golang.org/cl/4121043

src/pkg/unicode/Makefile

@@ -13,6 +13,8 @@ GOFILES=\
 
 include ../../Make.pkg
 
+CLEANFILES+=maketables
+
 maketables: maketables.go
 	$(GC) maketables.go
 	$(LD) -o maketables maketables.$O
@@ -21,9 +23,12 @@ tables:	maketables
 	./maketables --tables=all > tables.go
 	gofmt -w tables.go
 
+# Build (but do not run) maketables during testing,
+# just to make sure it still compiles.
+test: maketables
+
+# Downloads from www.unicode.org, so not part
+# of standard test scripts.
 testtables: maketables
 	@echo '***' Be sure to make tables and make install first
 	./maketables -test
-
-all: maketables
-CLEANFILES+=maketables