patch 8.0.0191: can't build with Ruby on some systems

Problem:    Some systems do not have ruby_sysinit(), causing the build to
            fail.
Solution:   Clean up how ruby_sysinit() and NtInitialize() are used. (Taro
            Muraoka)
diff --git a/src/if_ruby.c b/src/if_ruby.c
index 509d2f6..afa27ab 100644
--- a/src/if_ruby.c
+++ b/src/if_ruby.c
@@ -303,6 +303,7 @@
 # define ruby_init_loadpath		dll_ruby_init_loadpath
 # ifdef WIN3264
 #  define NtInitialize			dll_NtInitialize
+#  define ruby_sysinit			dll_ruby_sysinit
 #  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER >= 18
 #   define rb_w32_snprintf		dll_rb_w32_snprintf
 #  endif
@@ -405,6 +406,7 @@
 static void (*dll_ruby_init_loadpath) (void);
 # ifdef WIN3264
 static void (*dll_NtInitialize) (int*, char***);
+static void (*dll_ruby_sysinit) (int*, char***);
 #  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER >= 18
 static int (*dll_rb_w32_snprintf)(char*, size_t, const char*, ...);
 #  endif
@@ -594,13 +596,11 @@
     {"ruby_init", (RUBY_PROC*)&dll_ruby_init},
     {"ruby_init_loadpath", (RUBY_PROC*)&dll_ruby_init_loadpath},
 # ifdef WIN3264
-    {
 #  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER < 19
-    "NtInitialize",
+    {"NtInitialize", (RUBY_PROC*)&dll_NtInitialize},
 #  else
-    "ruby_sysinit",
+    {"ruby_sysinit", (RUBY_PROC*)&dll_ruby_sysinit},
 #  endif
-			(RUBY_PROC*)&dll_NtInitialize},
 #  if defined(DYNAMIC_RUBY_VER) && DYNAMIC_RUBY_VER >= 18
     {"rb_w32_snprintf", (RUBY_PROC*)&dll_rb_w32_snprintf},
 #  endif
diff --git a/src/version.c b/src/version.c
index 2094db7..bf4b82d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    191,
+/**/
     190,
 /**/
     189,