added support for versioned symbols on Linux

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@17668 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

acinclude.m4

@@ -382,6 +382,57 @@ AC_DEFUN([WX_ARG_ENABLE],
         ])
 
 
+dnl ===========================================================================
+dnl Linker features test
+dnl ===========================================================================
+
+dnl ---------------------------------------------------------------------------
+dnl WX_VERSIONED_SYMBOLS checks whether the linker can create versioned
+dnl symbols. If it can, sets LDFLAGS_VERSIONING to $CXX flags needed to use
+dnl version script file named versionfile
+dnl
+dnl call WX_VERSIONED_SYMBOLS(versionfile)
+dnl ---------------------------------------------------------------------------
+AC_DEFUN([WX_VERSIONED_SYMBOLS],
+[
+  found_versioning=no
+
+  dnl Check for known non-gcc cases:
+  case "${host}" in
+    *-*-solaris2* )
+      if test "x$GCC" != "xyes" ; then
+          LDFLAGS_VERSIONING="-M $1"
+          found_versioning=yes
+      fi
+    ;;
+  esac
+  
+  dnl Generic check for GCC or GCC-like behaviour (Intel C++, GCC):
+  if test $found_versioning = no ; then
+      AC_CACHE_CHECK([if the linker accepts --version-script], wx_cv_version_script,
+      [
+        echo "VER_1 { *; };" >conftest.sym
+        echo "int main() { return 0; }" >conftest.cpp
+  
+        if AC_TRY_COMMAND([
+                $CXX -o conftest.output $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.cpp
+                -Wl,--version-script,conftest.sym >/dev/null 2>conftest.stderr]) ; then
+          if test -s conftest.stderr ; then
+              wx_cv_version_script=no
+          else
+              wx_cv_version_script=yes
+          fi
+        else
+          wx_cv_version_script=no
+        fi
+        rm -f conftest.output conftest.stderr conftest.sym conftest.cpp
+      ])
+      if test $wx_cv_version_script = yes ; then
+        LDFLAGS_VERSIONING="-Wl,--version-script,$1"
+      fi
+  fi
+])
+
 
 dnl ===========================================================================
 dnl "3rd party" macros included here because they are not widely available