configure.ac: Fix trailing whitespace

Change-Id: Ia7b0ff11e58375842be15823d6b5dcaafc0f1f82
diff --git a/configure.ac b/configure.ac
index e31cef1..861a977 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,7 +19,7 @@
 AC_PROG_CPP
 LT_INIT
 
-dnl patching ${archive_cmds} to affect generation of file "libtool" to fix linking with clang 
+dnl patching ${archive_cmds} to affect generation of file "libtool" to fix linking with clang
 AS_CASE(["$LD"],[*clang*],
   [AS_CASE(["${host_os}"],
      [*linux*],[archive_cmds='$CC -shared $pic_flag $libobjs $deplibs $compiler_flags $wl-soname $wl$soname -o $lib'])])