Use PANDOC env-var to control which pandoc binary is used

Author: tarleb

include-files/Makefile

@@ -1,15 +1,16 @@
 DIFF ?= diff --strip-trailing-cr -u
+PANDOC ?= pandoc
 
 test: sample.md file-a.md file-b.md file-c.md include-files.lua
-	@pandoc --lua-filter=include-files.lua --to=native $< \
+	@$(PANDOC) --lua-filter=include-files.lua --to=native $< \
 	    | $(DIFF) expected.native -
-	@pandoc --lua-filter=include-files.lua -M include-auto --to=native $< \
+	@$(PANDOC) --lua-filter=include-files.lua -M include-auto --to=native $< \
 	    | $(DIFF) expected-auto.native -
 
 expected.native: sample.md file-a.md file-b.md file-c.md include-files.lua
-	pandoc --lua-filter=include-files.lua --output $@ $<
+	$(PANDOC) --lua-filter=include-files.lua --output $@ $<
 
 expected-auto.native: sample.md file-a.md file-b.md file-c.md include-files.lua
-	pandoc --lua-filter=include-files.lua -M include-auto --output $@ $<
+	$(PANDOC) --lua-filter=include-files.lua -M include-auto --output $@ $<
 
 .PHONY: test