maint: avoid syntax-check failures

'make syntax-check' failed with:

  locate/word_io.h:
  maint.mk: the above files include assert.h but don't use it
  maint.mk:479: recipe for target 'sc_prohibit_assert_without_use' failed
  ...
  lib/bugreports.h:
  maint.mk: empty line(s) or no newline at EOF
  maint.mk:929: recipe for target 'sc_prohibit_empty_lines_at_EOF' failed

* locate/word_io.h (#include <assert.h>): Remove superfluous inclusion
of <assert.h>.
* lib/bugreports.h: Remove stray empty line at EOF.

lib/bugreports.h

@@ -23,7 +23,4 @@
 /* Interpreetation of the return code is as for fprintf. */
 int explain_how_to_report_bugs (FILE *f, const char *program_name);
 
-
 #endif
-
-

locate/word_io.c

@@ -19,7 +19,6 @@
 #include <config.h>
 
 /* system headers. */
-#include <assert.h>
 #include <errno.h>
 #include <stdbool.h>		/* for bool */
 #include <stdio.h>