ax_lib_hdf5.m4: extra space in the include path flag

Hi,

In the latest version of ax_lib_hdf5.m4 (serial 10), the code parsing 
the output of h5cc for the "Installation point:" results in an extra 
leading space. The space creeps into HDF5_CPPFLAGS and breaks the 
include path flag into two tokens, e.g., "-I" and "/usr/include".  While 
this may be legal and doesn't affect the compilation, it does break some 
library tools (e.g.,  when the macro is used in building a dynamic 
library that uses pkg-config). Please see the attached patch for a 
proposed fix for the situation.

With best wishes,

Chun-Chung Chen

--- ax_lib_hdf5.m4.orig	2014-10-23 17:44:48.581899734 +0800
+++ ax_lib_hdf5.m4	2014-10-23 17:34:23.885322446 +0800
@@ -206,7 +206,7 @@
         dnl Find the installation directory and append include/
         HDF5_tmp_inst=$(eval $H5CC -showconfig \
             | $GREP 'Installation point:' \
-            | $AWK -F: '{print $[]2}' )
+            | $AWK '{print $[]NF}' )
 
         dnl Add this to the CPPFLAGS
         HDF5_CPPFLAGS="-I${HDF5_tmp_inst}/include"