Add curly-brace code folding

Author: jrudess

doc/verilog_systemverilog.txt

@@ -445,6 +445,7 @@ Default: undefined
           - `block_nested` (like "block", but allows nesting)
           - `block_named` (like "block", but allows nesting and only folds if `begin` is labelled)
         - `comment` (`/*..*/`)
+        - `curly` (`{ .. }`)
         - `define` (preprocessor conditional statement)
         - `instance`
         - `all` (enables all above options)

syntax/verilog_systemverilog.vim

@@ -286,6 +286,17 @@ else
     syn keyword verilogStatement  begin end
 endif
 
+if index(s:verilog_syntax_fold, "curly") >= 0 || index(s:verilog_syntax_fold, "all") >= 0
+    syn region verilogCurlyBlock
+        \ matchgroup=verilogOperator
+        \ start="{"
+        \ skip="/[*/].*"
+        \ end="}"
+        \ fold
+        \ transparent
+        \ contains=TOP
+endif
+
 if index(s:verilog_syntax_fold, "define") >= 0 || index(s:verilog_syntax_fold, "all") >= 0
     syn region verilogIfdef
         \ start="`ifn\?def\>"