Use full bin path names when executing grumpy tools. Otherwise some...

Use full bin path names when executing grumpy tools. Otherwise some invocations fail with "no such file or directory" on Make 3.81 on OS X.

Makefile

@@ -63,6 +63,8 @@ BENCHMARK_BINS := $(patsubst %,build/%_benchmark,$(BENCHMARKS))
 
 TOOL_BINS = $(patsubst %,build/bin/%,benchcmp coverparse diffrange)
 
+GOLINT_BIN = build/bin/golint
+
 all: $(COMPILER) $(RUNTIME) $(STDLIB) $(TOOL_BINS)
 
 benchmarks: $(BENCHMARK_BINS)
@@ -72,7 +74,7 @@ clean:
 
 # Convenient wrapper around grumprun that avoids having to set up PATH, etc.
 run: $(RUNNER)
-	@grumprun
+	@$(RUNNER_BIN)
 
 test: $(ACCEPT_PASS_FILES) $(COMPILER_PASS_FILES) $(COMPILER_EXPR_VISITOR_PASS_FILES) $(COMPILER_STMT_PASS_FILES) $(RUNTIME_PASS_FILE) $(STDLIB_PASS_FILES)
 
@@ -135,25 +137,25 @@ $(RUNTIME_COVER_FILE): $(RUNTIME) $(filter %_test.go,$(RUNTIME_SRCS))
 cover: $(RUNTIME_COVER_FILE) $(TOOL_BINS)
 	@bash -c 'comm -12 <(coverparse $< | sed "s/^grumpy/runtime/" | sort) <(git diff --dst-prefix= $(DIFF_COMMIT) | diffrange | sort)' | sort -t':' -k1,1 -k2n,2 | sed 's/$$/: missing coverage/' | tee errors.err
 
-build/bin/golint:
+$(GOLINT_BIN):
 	@go get -u github.com/golang/lint/golint
 
-lint: build/bin/golint
-	@golint runtime
+lint: $(GOLINT_BIN)
+	@$(GOLINT_BIN) runtime
 
 # ------------------------------------------------------------------------------
 # Standard library
 # ------------------------------------------------------------------------------
 
 $(STDLIB_PASS_FILES): $(PKG_DIR)/grumpy/lib/%.pass: $(PKG_DIR)/grumpy/lib/%.a
-	@grumprun -m `echo $* | tr / .`
+	@$(RUNNER_BIN) -m `echo $* | tr / .`
 	@touch $@
 	@echo 'lib/$* PASS'
 
 define GRUMPY_STDLIB
 build/src/grumpy/lib/$(2)/module.go: $(1) $(COMPILER)
 	@mkdir -p build/src/grumpy/lib/$(2)
-	@grumpc -modname=$(notdir $(2)) $(1) > $$@
+	@$(COMPILER_BIN) -modname=$(notdir $(2)) $(1) > $$@
 
 build/src/grumpy/lib/$(2)/module.d: $(1)
 	@mkdir -p build/src/grumpy/lib/$(2)
@@ -175,7 +177,7 @@ $(eval $(foreach x,$(shell seq $(words $(STDLIB_SRCS))),$(call GRUMPY_STDLIB,$(w
 
 $(patsubst %_test,build/%.go,$(ACCEPT_TESTS)): build/%.go: %_test.py $(COMPILER)
 	@mkdir -p $(@D)
-	@grumpc $< > $@
+	@$(COMPILER_BIN) $< > $@
 
 # TODO: These should not depend on stdlibs and should instead build a .d file.
 $(patsubst %,build/%,$(ACCEPT_TESTS)): build/%_test: build/%.go $(RUNTIME) $(STDLIB)
@@ -189,7 +191,7 @@ $(ACCEPT_PASS_FILES): build/%_test.pass: build/%_test
 
 $(patsubst %,build/%.go,$(BENCHMARKS)): build/%.go: %.py $(COMPILER)
 	@mkdir -p $(@D)
-	@grumpc $< > $@
+	@$(COMPILER_BIN) $< > $@
 
 $(BENCHMARK_BINS): build/benchmarks/%_benchmark: build/benchmarks/%.go $(RUNTIME) $(STDLIB)
 	@mkdir -p $(@D)