Uses autotools to idenfiy if sys/utsname.h is present

Fix build problem on the msc_status_engine, reported by: Walter Hop and
Derek Werthmuller.

Author: Felipe Zimmerle

apache2/msc_status_engine.c

@@ -14,6 +14,7 @@
 
 #include "msc_status_engine.h"
 #include "apr_sha1.h"
+#include "modsecurity_config.h"
 
 #ifdef WIN32
 #include <winsock2.h>
@@ -26,20 +27,20 @@
 #include <net/if.h>
 #include <net/if_dl.h>
 #include <netinet/in.h>
-#include <sys/utsname.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #ifndef IFT_ETHER
 #define IFT_ETHER 0x6 /* Ethernet CSMACD */
 #endif
 #endif
 
-#ifdef __gnu_linux__
-#include <sys/utsname.h>
+#if (defined(__linux__) || defined(__gnu_linux__))
 #include <linux/if.h>
 #include <linux/sockios.h>
 #endif
-
+#ifdef HAVE_SYS_UTSNAME_H
+#include <sys/utsname.h>
+#endif
 
 // Bese32 encode, based on:
 // https://code.google.com/p/google-authenticator/source/browse/libpam/base32.c
@@ -133,7 +134,9 @@ int DSOLOCAL msc_status_engine_machine_name(char *machine_name, size_t len) {
     if (GetComputerName(machine_name, &lenComputerName) == 0) {
         goto failed;
     }
-#else
+#endif
+
+#ifdef HAVE_SYS_UTSNAME_H
    static struct utsname u;
 
    if ( uname( &u ) < 0 ) {
@@ -180,7 +183,7 @@ int DSOLOCAL msc_status_engine_mac_address (unsigned char *mac)
     freeifaddrs( ifaphead );
 #endif
 
-#if __gnu_linux__
+#if (defined(__linux__) || defined(__gnu_linux__))
     struct ifconf conf;
     int sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP );
     struct ifreq* ifr;

configure.ac

@@ -33,7 +33,7 @@ AC_PATH_PROGS(ENV_CMD, [env printenv], )
 
 # Checks for header files.
 AC_HEADER_STDC
-AC_CHECK_HEADERS([fcntl.h limits.h stdlib.h string.h unistd.h sys/types.h sys/stat.h])
+AC_CHECK_HEADERS([fcntl.h limits.h stdlib.h string.h unistd.h sys/types.h sys/stat.h sys/utsname.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST