patch 8.0.1256: typo in configure variable vim_cv_tgent

Problem:    Typo in configure variable vim_cv_tgent. (Matthieu Guillard)
Solution:   Rename the variable. (closes #2281)
diff --git a/src/auto/configure b/src/auto/configure
index 467f9dc..16cbcf3 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -11553,7 +11553,7 @@
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking what tgetent() returns for an unknown terminal" >&5
 $as_echo_n "checking what tgetent() returns for an unknown terminal... " >&6; }
-if ${vim_cv_tgent+:} false; then :
+if ${vim_cv_tgetent+:} false; then :
   $as_echo_n "(cached) " >&6
 else
 
@@ -11579,11 +11579,11 @@
 _ACEOF
 if ac_fn_c_try_run "$LINENO"; then :
 
-      vim_cv_tgent=zero
+      vim_cv_tgetent=zero
 
 else
 
-      vim_cv_tgent=non-zero
+      vim_cv_tgetent=non-zero
 
 fi
 rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
@@ -11592,10 +11592,10 @@
 
 
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $vim_cv_tgent" >&5
-$as_echo "$vim_cv_tgent" >&6; }
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $vim_cv_tgetent" >&5
+$as_echo "$vim_cv_tgetent" >&6; }
 
-if test "x$vim_cv_tgent" = "xzero" ; then
+if test "x$vim_cv_tgetent" = "xzero" ; then
   $as_echo "#define TGETENT_ZERO_ERR 0" >>confdefs.h
 
 fi
diff --git a/src/configure.ac b/src/configure.ac
index f4c0194..e287124 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -3388,7 +3388,7 @@
   AC_DEFINE(TERMINFO)
 fi
 
-AC_CACHE_CHECK([what tgetent() returns for an unknown terminal], [vim_cv_tgent],
+AC_CACHE_CHECK([what tgetent() returns for an unknown terminal], [vim_cv_tgetent],
   [
     AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include "confdefs.h"
@@ -3402,15 +3402,15 @@
 main()
 {char s[10000]; int res = tgetent(s, "thisterminaldoesnotexist"); exit(res != 0); }
     ]])],[
-      vim_cv_tgent=zero
+      vim_cv_tgetent=zero
     ],[
-      vim_cv_tgent=non-zero
+      vim_cv_tgetent=non-zero
     ],[
       AC_MSG_ERROR(failed to compile test program.)
     ])
   ])
 
-if test "x$vim_cv_tgent" = "xzero" ; then
+if test "x$vim_cv_tgetent" = "xzero" ; then
   AC_DEFINE(TGETENT_ZERO_ERR, 0)
 fi
 
diff --git a/src/version.c b/src/version.c
index 8cc9bba..e94b81a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1256,
+/**/
     1255,
 /**/
     1254,