configure: Accept LLVM 3.5 for building rust

This is the current head of LLVM, and we can indeed build with 3.5

configure

@@ -604,7 +604,7 @@ then
     LLVM_VERSION=$($LLVM_CONFIG --version)
 
     case $LLVM_VERSION in
-        (3.[2-4]svn|3.[2-4])
+        (3.[2-5]svn|3.[2-5])
             msg "found ok version of LLVM: $LLVM_VERSION"
             ;;
         (*)
@@ -626,7 +626,7 @@ then
                       | cut -d ' ' -f 2)
 
     case $CFG_CLANG_VERSION in
-        (3.0svn | 3.0 | 3.1* | 3.2* | 3.3* | 3.4* )
+        (3.0svn | 3.0 | 3.1* | 3.2* | 3.3* | 3.4* | 3.5* )
         step_msg "found ok version of CLANG: $CFG_CLANG_VERSION"
         CFG_C_COMPILER="clang"
         ;;