Add a configure script to make compiling on Linux easier

Makefile

@@ -1,6 +1,8 @@
+include config.mk
+
 PREFIX?=/usr/local/
 CFLAGS  += -pedantic -Wall -Wextra -Wmissing-prototypes \
-           -Wstrict-prototypes -Wwrite-strings
+           -Wstrict-prototypes -Wwrite-strings ${EXTRAFLAGS}
 
 .SUFFIXES: .c .o
 

README.md

@@ -25,11 +25,12 @@ For all supported OS, it's possible to run **Vger** in a chroot and drop privile
 ```
 git clone https://tildegit.org/solene/vger.git
 cd vger
+./configure (only really useful for Linux)
 make
 doas make install
 ```
 
-On GNU/Linux, make sure you installed `libbsd`.
+On GNU/Linux, make sure you installed `libbsd`, it has been reported that using clang was required too.
 
 # Running tests
 

config.mk

@@ -0,0 +1 @@
+EXTRAFLAGS=

utils.c

@@ -3,12 +3,17 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 #include <syslog.h>
 #include <unistd.h>
 
 #include "utils.h"
 
+#ifdef __OpenBSD__
+#include <string.h>
+#else
+#include <bsd/string.h>
+#endif
+
 #ifdef __OpenBSD__
 void
 eunveil(const char *path, const char *permissions)