Add missing CMake module for built-in svn-client support.

Thanks to Martin for spotting this.

CMakeModules/FindSvnClient.cmake

@@ -0,0 +1,48 @@
+# Find Subversion client libraries, and dependencies
+# including APR (Apache Portable Runtime)
+
+include (CheckFunctionExists)
+include (CheckIncludeFile)
+
+find_program(HAVE_APR_CONFIG apr-1-config)
+if(HAVE_APR_CONFIG) 
+        
+    execute_process(COMMAND apr-1-config --cppflags --includes
+        OUTPUT_VARIABLE APR_CFLAGS
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+        
+    execute_process(COMMAND apr-1-config --link-ld
+        OUTPUT_VARIABLE RAW_APR_LIBS
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+    
+# clean up some vars, or other CMake pieces complain
+	string(STRIP ${RAW_APR_LIBS} APR_LIBS)
+
+else(HAVE_APR_CONFIG)
+    message(STATUS "apr-1-config not found, implement manual search for APR")
+endif(HAVE_APR_CONFIG)
+
+find_path(LIBSVN_INCLUDE_DIR svn_client.h
+  HINTS
+  $ENV{LIBSVN_DIR}
+  PATH_SUFFIXES include/subversion-1
+  PATHS
+  /usr/local
+  /usr
+  /opt
+)
+
+check_library_exists(svn_client-1 svn_client_checkout "" HAVE_LIB_SVNCLIENT)
+check_library_exists(svn_subr-1 svn_cmdline_init "" HAVE_LIB_SVNSUBR)
+check_library_exists(svn_ra-1 svn_ra_initialize "" HAVE_LIB_SVNRA)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(LIBSVN DEFAULT_MSG 
+    HAVE_LIB_SVNSUBR 
+    HAVE_LIB_SVNCLIENT
+    HAVE_LIB_SVNRA 
+    LIBSVN_INCLUDE_DIR)
+
+if(LIBSVN_FOUND)
+    set(LIBSVN_LIBRARIES "svn_client-1" "svn_subr-1" "svn_ra-1" ${APR_LIBS})
+endif(LIBSVN_FOUND)