add mdate, a portable version of GNU date --rfc-2822

Makefile

@@ -1,11 +1,12 @@
 CFLAGS=-g -O2 -Wall -Wno-switch -Wextra -fstack-protector-strong -D_FORTIFY_SOURCE=2
 
-ALL = maddr magrep mdeliver mdirs mflag mgenmid mhdr minc mlist mmime mpick mscan msed mseq mshow msort mthread
+ALL = maddr magrep mdate mdeliver mdirs mflag mgenmid mhdr minc mlist mmime mpick mscan msed mseq mshow msort mthread
 
 all: $(ALL)
 
 maddr: maddr.o blaze822.o seq.o rfc2047.o mymemmem.o
 magrep: magrep.o blaze822.o seq.o rfc2045.o rfc2047.o mymemmem.o
+mdate: mdate.o
 mdeliver: mdeliver.o blaze822.o mymemmem.o
 mdirs: mdirs.o
 mflag: mflag.o blaze822.o seq.o mymemmem.o

mdate.c

@@ -0,0 +1,15 @@
+#include <time.h>
+#include <unistd.h>
+
+int
+main() {
+	char buf[64];
+	time_t now = time(0);
+
+	ssize_t l = strftime(buf, sizeof buf,
+	    "%a, %d %b %Y %T %z\n", localtime(&now));
+	if (write(1, buf, l) == l)
+		return 0;
+
+	return 1;
+}