[patch, libgfortran] Fix m4 file generation

[FX Coudert]

Also, with your patch, some of the regenerated files (that are  
regenerated before the build failure) are wrong:

Index: generated/cshift1_4.c
===================================================================
--- generated/cshift1_4.c       (revision 121774)
+++ generated/cshift1_4.c       (working copy)
@@ -55,7 +55,7 @@
    index_type soffset;
    const char *sptr;
    const char *src;
-  /* h.* indicates the shift array.  */
+  /* h.* indicates the  array.  */
    index_type hstride[GFC_MAX_DIMENSIONS];
    index_type hstride0;
    const GFC_INTEGER_4 *hptr;
@@ -144,7 +144,7 @@
    while (rptr)
      {
-      /* Do the shift for this dimension.  */
+      /* Do the  for this dimension.  */
        sh = *hptr;
        sh = (div (sh, len)).rem;
        if (sh < 0)