Remove trailing whitespace

configure

@@ -560,10 +560,10 @@ then
         step_msg "on OS X 10.9, forcing use of clang"
         CFG_ENABLE_CLANG=1
         putvar CFG_ENABLE_CLANG
-    else 
-        # on OS X, with xcode 5 and newer, certain developers may have 
+    else
+        # on OS X, with xcode 5 and newer, certain developers may have
         # cc, gcc and g++ point to a  mixture of clang and gcc
-        # if so, this will create very strange build errors 
+        # if so, this will create very strange build errors
         # this last stanza is to detect some such problems and save the future rust
         # contributor some time solving that issue.
         # this detection could be generalized to other OSes aside from OS X
@@ -576,8 +576,8 @@ then
         # note that for xcode 5, g++ points to clang, not clang++
         if !((chk_cc gcc clang  && chk_cc g++ clang) ||
             (chk_cc gcc gcc  &&( chk_cc g++ g++ || chk g++ gcc))) then
-            err "the gcc and g++ in your path point to different compilers. 
-Check which versions are in your path with  cc --version and g++ --version. 
+            err "the gcc and g++ in your path point to different compilers.
+Check which versions are in your path with  cc --version and g++ --version.
 To resolve this problem, either fix your PATH  or run configure with --enable-clang"
         fi