patch 9.0.1234: the code style has to be checked manually

Problem:    The code style has to be checked manually.
Solution:   Add basic code style checks in a test.  Fix or avoid uncovered
            problems.

src/nv_cmds.h

@@ -25,7 +25,8 @@
 /*
  * Used when building Vim.
  */
-# define NVCMD(a, b, c, d)  {a, b, c, d}
+# define NVCMD(a, b, c, d) \
+	{a, b, c, d}
 
 #ifdef FEAT_GUI
 #define NV_VER_SCROLLBAR	nv_ver_scrollbar