Give absolute path for #include to AC_CHECK_HEADERS().

Taken from Etienne Dechamp's patch to support VPATH builds for tinc 1.1.

diff --git a/configure.ac b/configure.ac
index 0448707..c37cb28 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -180,18 +180,16 @@ dnl Checks for libraries.
 dnl Checks for header files.
 dnl We do this in multiple stages, because unlike Linux all the other operating systems really suck and don't include their own dependencies.
 
-save_CPPFLAGS="$CPPFLAGS"
-CPPFLAGS="$CPPFLAGS -I${srcdir}"
 AC_HEADER_STDC
 AC_CHECK_HEADERS([stdbool.h syslog.h sys/file.h sys/ioctl.h sys/mman.h sys/param.h sys/resource.h sys/socket.h sys/time.h time.h sys/uio.h sys/wait.h netdb.h arpa/inet.h arpa/nameser.h dirent.h getopt.h])
 AC_CHECK_HEADERS([net/if.h net/if_types.h linux/if_tun.h net/if_tun.h net/if_utun.h net/tun/if_tun.h net/if_tap.h net/tap/if_tap.h net/ethernet.h net/if_arp.h netinet/in_systm.h netinet/in.h netinet/in6.h netpacket/packet.h],
-  [], [], [#include "src/have.h"]
+  [], [], [#include "$srcdir/src/have.h"]
 )
 AC_CHECK_HEADERS([netinet/if_ether.h netinet/ip.h netinet/ip6.h resolv.h],
-  [], [], [#include "src/have.h"]
+  [], [], [#include "$srcdir/src/have.h"]
 )
 AC_CHECK_HEADERS([netinet/tcp.h netinet/ip_icmp.h netinet/icmp6.h],
-  [], [], [#include "src/have.h"]
+  [], [], [#include "$srcdir/src/have.h"]
 )
 
 dnl Checks for typedefs, structures, and compiler characteristics.
@@ -205,13 +203,13 @@ AC_STRUCT_TM
 tinc_ATTRIBUTE(__malloc__)
 
 AC_CHECK_TYPES([socklen_t, struct ether_header, struct arphdr, struct ether_arp, struct in_addr, struct addrinfo, struct ip, struct icmp, struct in6_addr, struct sockaddr_in6, struct ip6_hdr, struct icmp6_hdr, struct nd_neighbor_solicit, struct nd_opt_hdr], , ,
-  [#include "src/have.h"]
+  [#include "$srcdir/src/have.h"]
 )
 
 dnl Checks for library functions.
 AC_TYPE_SIGNAL
 AC_CHECK_FUNCS([asprintf daemon fchmod flock ftime fork get_current_dir_name gettimeofday mlockall pselect putenv random select strdup strerror strsignal strtol system unsetenv usleep vsyslog writev devname fdevname],
-  [], [], [#include "src/have.h"]
+  [], [], [#include "$srcdir/src/have.h"]
 )
 
 AC_CHECK_FUNC(getopt_long, [getopt=true; AC_DEFINE(HAVE_GETOPT_LONG, 1, [getopt_long()])], [getopt=false])
@@ -227,11 +225,9 @@ AC_CHECK_FUNC(gethostbyname, [], [
 ])
 
 AC_CHECK_DECLS([freeaddrinfo, gai_strerror, getaddrinfo, getnameinfo],
-  [], [], [#include "src/have.h"]
+  [], [], [#include "$srcdir/src/have.h"]
 )
 
-CPPFLAGS="$save_CPPFLAGS"
-
 AC_CHECK_DECLS([res_init], [AC_CHECK_LIB(resolv, res_init)], [], [
   #include <netinet/in.h>
   #include <resolv.h>