patch 9.1.0274: MS-Windows: a few compiler warnings

Problem:  MS-Windows: a few compiler warnings
Solution: Change variable types to resolve compiler warnings
          (Mike Williams)

Windows compiles were reporting a few size_t to signed integer
conversion warnings that can be resolved by changing the variable
declarations to be size_t to start with.

closes: #14429

Signed-off-by: Mike Williams <mrmrdubya@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/getchar.c b/src/getchar.c
index 179c50c..c8dde22 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -81,7 +81,7 @@
 static char_u	typebuf_init[TYPELEN_INIT];	// initial typebuf.tb_buf
 static char_u	noremapbuf_init[TYPELEN_INIT];	// initial typebuf.tb_noremap
 
-static int	last_recorded_len = 0;	// number of last recorded chars
+static size_t	last_recorded_len = 0;	// number of last recorded chars
 
 #ifdef FEAT_EVAL
 mapblock_T	*last_used_map = NULL;
@@ -163,7 +163,7 @@
      * (possibly mapped) characters that stopped the recording.
      */
     len = STRLEN(p);
-    if ((int)len >= last_recorded_len)
+    if (len >= last_recorded_len)
     {
 	len -= last_recorded_len;
 	p[len] = NUL;
@@ -1789,7 +1789,7 @@
     else
     {
 	// number of characters recorded from the last vgetc() call
-	static int	last_vgetc_recorded_len = 0;
+	static size_t	last_vgetc_recorded_len = 0;
 
 	mod_mask = 0;
 	vgetc_mod_mask = 0;