patch 8.2.4623: Coverity warns for using uninitialized field

Problem:    Coverity warns for using uninitialized field.
Solution:   Initialize he field to zero.
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 65f4221..5e7cb83 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -3906,6 +3906,7 @@
     // For ":2match" and ":3match" we need to skip the number.
     ea.cmd = (*name == '2' || *name == '3') ? name + 1 : name;
     ea.cmdidx = (cmdidx_T)0;
+    ea.flags = 0;
     p = find_ex_command(&ea, &full, NULL, NULL);
     if (p == NULL)
 	return 3;