Add a directory for tests that exercise the supported C standard differences.

As a first test added the snippet given in issue #1670

test/standard/Makefile

@@ -0,0 +1,63 @@
+# Makefile for the regression tests that return an error code on failure
+
+ifneq ($(shell echo),)
+  CMD_EXE = 1
+endif
+
+ifdef CMD_EXE
+  S = $(subst /,\,/)
+  NULLDEV = nul:
+  MKDIR = mkdir $(subst /,\,$1)
+  RMDIR = -rmdir /s /q $(subst /,\,$1)
+else
+  S = /
+  NULLDEV = /dev/null
+  MKDIR = mkdir -p $1
+  RMDIR = $(RM) -r $1
+endif
+
+ifdef QUIET
+  .SILENT:
+  NULLOUT = >$(NULLDEV)
+  NULLERR = 2>$(NULLDEV)
+endif
+
+SIM65FLAGS = -x 5000000000 -c
+
+CC65 := $(if $(wildcard ../../bin/cc65*),..$S..$Sbin$Scc65,cc65)
+CA65 := $(if $(wildcard ../../bin/ca65*),..$S..$Sbin$Sca65,ca65)
+LD65 := $(if $(wildcard ../../bin/ld65*),..$S..$Sbin$Sld65,ld65)
+SIM65 := $(if $(wildcard ../../bin/sim65*),..$S..$Sbin$Ssim65,sim65)
+
+WORKDIR = ../../testwrk/standard
+
+OPTIONS = c89 c99 cc65
+
+.PHONY: all clean
+
+SOURCES := $(wildcard *.c)
+TESTS  = $(foreach option,$(OPTIONS),$(SOURCES:%.c=$(WORKDIR)/%.$(option).6502.prg))
+#TESTS += $(foreach option,$(OPTIONS),$(SOURCES:%.c=$(WORKDIR)/%.$(option).65c02.prg))
+
+all: $(TESTS)
+
+$(WORKDIR):
+	$(call MKDIR,$(WORKDIR))
+
+define PRG_template
+
+$(WORKDIR)/%.$1.$2.prg: %.c | $(WORKDIR)
+	$(if $(QUIET),echo standard/$$*.$1.$2.prg)
+	$(CC65) -t sim$2 $$(CC65FLAGS) -Osir --add-source --standard $1 -o $$(@:.prg=.s) $$< $(NULLERR)
+	$(CA65) -t sim$2 -o $$(@:.prg=.o) $$(@:.prg=.s) $(NULLERR)
+	$(LD65) -t sim$2 -o $$@ $$(@:.prg=.o) sim$2.lib $(NULLERR)
+	$(SIM65) $(SIM65FLAGS) $$@ > $(WORKDIR)/$$@.out
+
+endef # PRG_template
+
+$(foreach option,$(OPTIONS),$(eval $(call PRG_template,$(option),6502)))
+
+#$(foreach option,$(OPTIONS),$(eval $(call PRG_template,$(option),65c02)))
+
+clean:
+	@$(call RMDIR,$(WORKDIR))