patch 8.1.1973: cannot build without the quickfix feature

Problem:    Cannot build without the quickfix feature.
Solution:   Remove #ifdef for qf_info_T.

src/structs.h

@@ -2061,9 +2061,7 @@ typedef struct
 # define B_SPELL(buf)  (0)
 #endif
 
-#ifdef FEAT_QUICKFIX
 typedef struct qf_info_S qf_info_T;
-#endif
 
 #ifdef FEAT_PROFILE
 /*

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1973,
 /**/
     1972,
 /**/