Create Makefile for building with cosmocc

Resolves #9.

cosmopolitan/.gitignore

@@ -0,0 +1,2 @@
+/objdir/
+/out/

cosmopolitan/Makefile

@@ -0,0 +1,31 @@
+COSMOCC ?= ${HOME}/Downloads/cosmocc/bin/cosmocc
+
+OBJDIR = objdir
+OUTDIR = out
+
+SOURCES = \
+		../src/main.c \
+		../src/parser.c
+
+HEADERS = \
+		../src/parser.h
+
+OBJECTS = $(addprefix ${OBJDIR}/,$(subst ..,PREVDIR,$(patsubst %.c,%.c.o,${SOURCES})))
+
+all: actually_portable_simplearchiver
+
+actually_portable_simplearchiver: ${OBJECTS}
+	@mkdir -p "${OUTDIR}"
+	${COSMOCC} -o "${OUTDIR}/actually_portable_simplearchiver" $^
+
+.PHONY: clean
+
+clean:
+	rm -rf "${OUTDIR}"
+	rm -rf "${OBJDIR}"
+
+.SECONDEXPANSION:
+
+${OBJDIR}/%.c.o: $$(subst PREVDIR,..,%.c) ${HEADERS}
+	@mkdir -p "$(dir $@)"
+	${COSMOCC} -c ${OTHER_FLAGS} -o $@ $<