add headers for various function prototypes

--- a/main.c
+++ b/main.c
@@ -24,6 +24,7 @@
 
 #include <time.h>
 #include <stdio.h>
+#include <stdlib.h> /* exit */
 #include <unistd.h>
 #include <signal.h>
 #include <fcntl.h>
--- a/log.c
+++ b/log.c
@@ -37,6 +37,7 @@
 #include <unistd.h>
 #include <syslog.h>
 #include <stdio.h>
+#include <stdlib.h> /* exit */
 #include <stdarg.h>
 #include <errno.h>
 #include <signal.h>
@@ -78,6 +79,7 @@ make_msg(const char *fmt, va_list args)
 	strcpy(msg + sizeof(msg) - sizeof(truncated), truncated);
 }
 
+#define log my_log /* log is a math builtin */
 static void
 log(int priority, const char *fmt, va_list args)
 /* Log a message, described by "fmt" and "args", with the specified
--- a/matchrx.c
+++ b/matchrx.c
@@ -23,6 +23,7 @@
 
 
 #include <stdio.h>
+#include <string.h> /* memset */
 #include <regex.h>
 #include <stdarg.h>
 #include <stdlib.h>