patch 8.1.0239: now Ruby build fails on other systems

Problem:    Now Ruby build fails on other systems.
Solution:   Always define rb_intern. (Ken Takata, closes #3275)

src/if_ruby.c

@@ -253,12 +253,12 @@ static void ruby_vim_init(void);
 # define rb_hash_new			dll_rb_hash_new
 # define rb_inspect			dll_rb_inspect
 # define rb_int2inum			dll_rb_int2inum
-# ifndef rb_intern
+
+// ruby.h may redefine rb_intern to use RUBY_CONST_ID_CACHE(), but that won't
+// work.  Not using the cache appears to be the best solution.
+# undef rb_intern
 # define rb_intern			dll_rb_intern
-# endif
+
-# ifdef RUBY_CONST_ID_CACHE
-#  define rb_intern2			dll_rb_intern2
-# endif
 # if VIM_SIZEOF_INT < VIM_SIZEOF_LONG /* 64 bits only */
 #  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER <= 18
 #   define rb_fix2int			dll_rb_fix2int
@@ -394,9 +394,6 @@ static VALUE (*dll_rb_hash_new) (void);
 static VALUE (*dll_rb_inspect) (VALUE);
 static VALUE (*dll_rb_int2inum) (long);
 static ID (*dll_rb_intern) (const char*);
-# ifdef RUBY_CONST_ID_CACHE
-static ID (*dll_rb_intern2) (const char*, long);
-# endif
 # if VIM_SIZEOF_INT < VIM_SIZEOF_LONG /* 64 bits only */
 static long (*dll_rb_fix2int) (VALUE);
 static long (*dll_rb_num2int) (VALUE);
@@ -597,9 +594,6 @@ static struct
     {"rb_inspect", (RUBY_PROC*)&dll_rb_inspect},
     {"rb_int2inum", (RUBY_PROC*)&dll_rb_int2inum},
     {"rb_intern", (RUBY_PROC*)&dll_rb_intern},
-# ifdef RUBY_CONST_ID_CACHE
-    {"rb_intern2", (RUBY_PROC*)&dll_rb_intern2},
-# endif
 # if VIM_SIZEOF_INT < VIM_SIZEOF_LONG /* 64 bits only */
     {"rb_fix2int", (RUBY_PROC*)&dll_rb_fix2int},
     {"rb_num2int", (RUBY_PROC*)&dll_rb_num2int},

src/version.c

@@ -794,6 +794,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    239,
 /**/
     238,
 /**/