Don't use echo to create git_hash.h, collapses multiple spaces

Wasn't sufficiently quoting, but we don't need to use echo in the first place

Will reconsider using %e instead of %d later

src/sbbs3/targets.mk

@@ -157,8 +157,8 @@ FORCE:
 
 ifneq ($(GIT), NO)
 git_hash.h: FORCE ../../.git
-	$(QUIET)echo '#define GIT_HASH "'`git log -1 HEAD --format=%h`\" > $@.tmp
-	$(QUIET)echo '#define GIT_DATE "'`git log -1 HEAD --format=%cd '--date=format-local:%b %e %Y %H:%M'`\" >> $@.tmp
+	$(QUIET)git log -1 HEAD --format="#define GIT_HASH \"%h\"" > $@.tmp
+	$(QUIET)git log -1 HEAD --format="#define GIT_DATE \"%cd\"" '--date=format-local:%b %e %Y %H:%M' >> $@.tmp
 	$(QUIET)test -e $@ && diff $@.tmp $@ || cp $@.tmp $@
 	$(QUIET)rm -f $@.tmp