fix space that was breaking header install

(cherry picked from commit b022f9eb61c97cc72ce5521fdc75bd398019a3cd)
diff --git a/mingw-w64-headers/configure.ac b/mingw-w64-headers/configure.ac
index c5b695b..7884971 100644
--- a/mingw-w64-headers/configure.ac
+++ b/mingw-w64-headers/configure.ac
@@ -39,7 +39,7 @@
 
 # Checks for header files.
 
-BASEHEAD_LIST="crt/_bsd_types.h crt/_cygwin.h crt/_mingw.h crt/_mingw_mac.h crt/_mingw_print_push.h crt/_mingw_print_pop.h crt/_mingw_secapi.h crt/_mingw_unicode.h crt/_timeval.h crt/crtdefs.h crt/excpt.h crt/intrin.h crt/vadefs.h crt/tchar.h " $srcdir/include/*.h
+BASEHEAD_LIST="crt/_bsd_types.h crt/_cygwin.h crt/_mingw.h crt/_mingw_mac.h crt/_mingw_print_push.h crt/_mingw_print_pop.h crt/_mingw_secapi.h crt/_mingw_unicode.h crt/_timeval.h crt/crtdefs.h crt/excpt.h crt/intrin.h crt/vadefs.h crt/tchar.h "$srcdir/include/*.h
 SECHEAD_LIST="$srcdir/crt/sec_api/stralign_s.h"
 for i in dlg h16 hxx rh ver; do
   BASEHEAD_LIST="$BASEHEAD_LIST "$srcdir/include/*.$i