Fix bug when one command or environment variable is a prefix of another.

This bug was introduced in 09377f7.

charset.c

@@ -716,7 +716,7 @@ public LWCHAR get_wchar(constant char *sp)
 /*
  * Store a character into a UTF-8 string.
  */
-public void put_wchar(char **pp, LWCHAR ch)
+public void put_wchar(mutable char **pp, LWCHAR ch)
 {
  if (!utf_mode || ch < 0x80) 
  {

cmdbuf.c

@@ -1284,7 +1284,7 @@ public int cmd_char(char c)
 /*
  * Return the number currently in the command buffer.
  */
-public LINENUM cmd_int(long *frac)
+public LINENUM cmd_int(mutable long *frac)
 {
  constant char *p;
  LINENUM n = 0;

cvt.c

@@ -50,7 +50,7 @@ public int * cvt_alloc_chpos(size_t len)
  * Returns converted text in odst. The original offset of each
  * odst character (when it was in osrc) is returned in the chpos array.
  */
-public void cvt_text(char *odst, constant char *osrc, int *chpos, size_t *lenp, int ops)
+public void cvt_text(mutable char *odst, constant char *osrc, mutable int *chpos, mutable size_t *lenp, int ops)
 {
  char *dst;
  char *edst = odst;

decode.c

@@ -694,7 +694,8 @@ static int cmd_search(constant char *cmd, constant char *table, constant char *e
  * but not the end of the string in the command table.
  * The user's command is incomplete.
  */
- return (A_PREFIX);
+ if (a == A_INVALID)
+ a = A_PREFIX;
  } else
  {
  /*

screen.c

@@ -2478,7 +2478,7 @@ static int parse_color6(constant char **ps)
  * CV_4BIT: fg/bg values are OR of CV_{RGB} bits.
  * CV_6BIT: fg/bg values are integers entered by user.
  */
-public COLOR_TYPE parse_color(constant char *str, int *p_fg, int *p_bg)
+public COLOR_TYPE parse_color(constant char *str, mutable int *p_fg, mutable int *p_bg)
 {
  int fg;
  int bg;

search.c

@@ -1783,7 +1783,7 @@ public void osc8_search(int search_type, constant char *param, int matches)
  osc8_search_param = NULL;
  if (match != 0)
  {
- error("OSC8 link not found", NULL_PARG);
+ error("OSC 8 link not found", NULL_PARG);
  return;
  }
  jump_loc(pos, jump_sline);