gallium: add $(PROGS_DEPS) as dependencies for $(PROGS)

Commit 80ee3a440c added a PROGS_DEPS
definition, but no uses, even though it seems clearly intended
to be a set of additional dependencies for $(PROGS).

Correct this.

src/gallium/Makefile.template

@@ -40,7 +40,7 @@ depend: $(C_SOURCES) $(CPP_SOURCES) $(ASM_SOURCES) $(SYMLINKS) $(GENERATED_SOURC
 	touch depend
 	$(MKDEP) $(MKDEP_OPTIONS) $(INCLUDES) $(C_SOURCES) $(CPP_SOURCES) $(ASM_SOURCES) $(GENERATED_SOURCES) 2> /dev/null
 
-$(PROGS): % : %.o
+$(PROGS): % : %.o $(PROGS_DEPS)
 	$(LD) $(LDFLAGS) $(filter %.o,$^) -o $@ -Wl,--start-group  $(LIBS) -Wl,--end-group
 
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