vim-patch:7.4.1866

Problem:    Invalid memory access when exiting with EXITFREE defined.
            (Dominique Pelle)
Solution:   Set "really_exiting" and skip error messages.

a96732150c

This fails to build, due to a00c2e0ecb
removing really_exiting from globals.h, but the next commit fixes the
build failure.

src/nvim/version.c

@@ -574,7 +574,7 @@ static int included_patches[] = {
   // 1869 NA
   // 1868,
   1867,
-  // 1866,
+  1866,
   // 1865 NA
   // 1864 NA
   // 1863 NA