Fix compilation warnings in MinGW64 build using GCC 7

Reported by Richard Copley <rcopley@gmail.com>.
* src/w32heap.c (init_heap): Declare enable_lfh only for
mingw.org's MinGW build.

* src/w32console.c (w32con_write_glyphs):
* src/unexw32.c (get_section_info, COPY_CHUNK, unexec): Fix some
mismatches of data type vs format spec.

* src/w32fns.c (compute_tip_xy):
* src/w32proc.c (stop_timer_thread):
* src/w32notify.c (remove_watch):
* src/eval.c (internal_lisp_condition_case):
* src/editfns.c (Ftranslate_region_internal):
* src/data.c (Fmake_variable_buffer_local, cons_to_unsigned)
(cons_to_signed):
* src/buffer.c (fix_overlays_before): Initialize variables to
avoid compiler warnings.

* lib-src/etags.c (TeX_commands, process_file_name): Initialize
variables to avoid compilation warnings.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib-src/etags.c b/lib-src/etags.c
index 5e05c19c624..724cce63955 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, *tmp_name;
+  char *ext, *real_name = NULL, *tmp_name;
   int retval;
 
   canonicalize_filename (file);
@@ -5594,7 +5594,7 @@ TeX_commands (FILE *inf)
   linebuffer *key;
 
   char TEX_esc = '\0';
-  char TEX_opgrp, TEX_clgrp;
+  char TEX_opgrp = 0, TEX_clgrp = 0;
 
   /* Initialize token table once from environment. */
   if (TEX_toktab == NULL)