Improve --enable-gcc-warnings for MinGW64

This partially reverts my 2016-05-30 patch.  Apparently MinGW64
still requires pacifications that GCC 7.1.1 x86-64 (Fedora 26)
does not.  Also, pacify tparam.c, which isn’t used on Fedora.
* lib-src/etags.c (process_file_name, TeX_commands):
* src/buffer.c (fix_overlays_before):
* src/data.c (Fmake_variable_buffer_local, cons_to_unsigned)
(cons_to_signed):
* src/editfns.c (Ftranslate_region_internal):
Prefer UNINIT to some stray value, as this simplifies
code-reading later.
* src/eval.c (CACHEABLE): New macro.
(internal_lisp_condition_case): Use it.
* src/tparam.c (tparam1): Use FALLTHROUGH to pacify GCC.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib-src/etags.c b/lib-src/etags.c
index 724cce63955..38be60e9cbb 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -1528,7 +1528,7 @@ process_file_name (char *file, language *lang)
   fdesc *fdp;
   compressor *compr;
   char *compressed_name, *uncompressed_name;
-  char *ext, *real_name = NULL, *tmp_name;
+  char *ext, *real_name UNINIT, *tmp_name;
   int retval;
 
   canonicalize_filename (file);
@@ -5594,7 +5594,7 @@ TeX_commands (FILE *inf)
   linebuffer *key;
 
   char TEX_esc = '\0';
-  char TEX_opgrp = 0, TEX_clgrp = 0;
+  char TEX_opgrp UNINIT, TEX_clgrp UNINIT;
 
   /* Initialize token table once from environment. */
   if (TEX_toktab == NULL)