Fix compilation with with bionic libc.

This fixes bug 1147:

 bionic doesn't have an actual implementation of mlockall();
 mlockall() is merely in the headers but not actually in the library.
 This prevents Tor compilation with the bionic libc for Android handsets.

configure.in

@@ -628,6 +628,11 @@ if test x$tcmalloc = xyes ; then
    LDFLAGS="-ltcmalloc $LDFLAGS"
 fi
 
+# By default, we're going to assume we don't have mlockall()
+# bionic and other platforms have various broken mlockall subsystems
+# some of systems don't have a working mlockall, some aren't linkable
+AC_CHECK_FUNCS(mlockall)
+
 # Allow user to specify an alternate syslog facility
 AC_ARG_WITH(syslog-facility,
 [  --with-syslog-facility=LOG syslog facility to use (default=LOG_DAEMON)],

src/common/compat.c

@@ -2273,7 +2273,7 @@ tor_mlockall(void)
    * http://msdn.microsoft.com/en-us/library/aa366895(VS.85).aspx
    */
 
-#ifdef HAVE_SYS_MMAN_H
+#ifdef HAVE_MLOCKALL
   ret = tor_set_max_memlock();
   if (ret == 0) {
     /* Perhaps we only want to log this if we're in a verbose mode? */