Update AX_BOOST_BASE macro

m4/ax_boost_base.m4

@@ -33,7 +33,7 @@
 #   and this notice are preserved. This file is offered as-is, without any
 #   warranty.
 
-#serial 21
+#serial 27
 
 AC_DEFUN([AX_BOOST_BASE],
 [
@@ -92,11 +92,26 @@ if test "x$want_boost" = "xyes"; then
     libsubdirs="lib"
     ax_arch=`uname -m`
     case $ax_arch in
-      x86_64|ppc64|s390x|sparc64|aarch64)
+      x86_64)
+        libsubdirs="lib64 libx32 lib lib64"
+        ;;
+      ppc64|s390x|sparc64|aarch64|ppc64le)
         libsubdirs="lib64 lib lib64"
         ;;
     esac
 
+    dnl allow for real multi-arch paths e.g. /usr/lib/x86_64-linux-gnu. Give
+    dnl them priority over the other paths since, if libs are found there, they
+    dnl are almost assuredly the ones desired.
+    AC_REQUIRE([AC_CANONICAL_HOST])
+    libsubdirs="lib/${host_cpu}-${host_os} $libsubdirs"
+
+    case ${host_cpu} in
+      i?86)
+        libsubdirs="lib/i386-${host_os} $libsubdirs"
+        ;;
+    esac
+
     dnl first we check the system location for boost libraries
     dnl this location ist chosen if boost libraries are installed with the --layout=system option
     dnl or if you install boost with RPM
@@ -158,6 +173,10 @@ if test "x$want_boost" = "xyes"; then
     dnl if we found no boost with system layout we search for boost libraries
     dnl built and installed without the --layout=system option or for a staged(not installed) version
     if test "x$succeeded" != "xyes"; then
+        CPPFLAGS="$CPPFLAGS_SAVED"
+        LDFLAGS="$LDFLAGS_SAVED"
+        BOOST_CPPFLAGS=
+        BOOST_LDFLAGS=
         _version=0
         if test "$ac_boost_path" != ""; then
             if test -d "$ac_boost_path" && test -r "$ac_boost_path"; then
@@ -170,6 +189,12 @@ if test "x$want_boost" = "xyes"; then
                     VERSION_UNDERSCORE=`echo $_version | sed 's/\./_/'`
                     BOOST_CPPFLAGS="-I$ac_boost_path/include/boost-$VERSION_UNDERSCORE"
                 done
+                dnl if nothing found search for layout used in Windows distributions
+                if test -z "$BOOST_CPPFLAGS"; then
+                    if test -d "$ac_boost_path/boost" && test -r "$ac_boost_path/boost"; then
+                        BOOST_CPPFLAGS="-I$ac_boost_path"
+                    fi
+                fi
             fi
         else
             if test "$cross_compiling" != yes; then