patch 9.0.0666: spacing-combining characters handled as composing

Problem:    Spacing-combining characters handled as composing, causing text to
            take more space than expected.
Solution:   Handle characters marked with "Mc" not as composing.
            (closes #11282
diff --git a/runtime/tools/unicode.vim b/runtime/tools/unicode.vim
index aa260e6..630a581 100644
--- a/runtime/tools/unicode.vim
+++ b/runtime/tools/unicode.vim
@@ -158,7 +158,8 @@
   let end = -1
   let ranges = []
   for p in s:dataprops
-    if p[2] == 'Mn' || p[2] == 'Mc' || p[2] == 'Me'
+    " The 'Mc' property was removed, it does take up space.
+    if p[2] == 'Mn' || p[2] == 'Me'
       let n = ('0x' . p[0]) + 0
       if start >= 0 && end + 1 == n
         " continue with same range.