patch 8.0.1808: can't build without TGETENT

Problem:    Can't build without TGETENT.
Solution:   Add #ifdef
diff --git a/src/term.c b/src/term.c
index 37caf2b..8b69cc4 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1544,6 +1544,7 @@
 };
 #endif
 
+#ifdef HAVE_TGETENT
     static void
 get_term_entries(int *height, int *width)
 {
@@ -1642,6 +1643,7 @@
 	PC = *p;
 # endif
 }
+#endif
 
     static void
 report_term_error(char_u *error_msg, char_u *term)