LaTeX writer/template: small fix for unnumbered tables.

This improves on commit e13aa5c015,
which worked only for recent versions of longtable.

For older versions, we need to define a dummy counter `none`.

Closes #11201.  Thanks to @priiduonu for the solution.

data/templates/common.latex

@@ -69,6 +69,7 @@ $-- tables
 $--
 $if(tables)$
 \usepackage{longtable,booktabs,array}
+\newcounter{none} % for unnumbered tables
 $if(multirow)$
 \usepackage{multirow}
 $endif$

src/Text/Pandoc/Writers/LaTeX/Table.hs

@@ -98,7 +98,7 @@ tableToLaTeX inlnsToLaTeX blksToLaTeX tbl = do
   modify $ \s -> s{ stTable = True }
   notes <- notesToLaTeX <$> gets stNotes
   beamer <- gets stBeamer
-  let makeUnnumbered x = "{\\def\\LTcaptype{} % do not increment counter" $$ x $$ "}"
+  let makeUnnumbered x = "{\\def\\LTcaptype{none} % do not increment counter" $$ x $$ "}"
   return
     $ (if null capt then makeUnnumbered else id)
     $ "\\begin{longtable}[]" <>

test/command/7272.md

@@ -14,7 +14,7 @@
   </tbody>
 </table>
 ^D
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}
   >{\raggedright\arraybackslash}p{(\linewidth - 0\tabcolsep) * \real{1.0000}}@{}}
 \toprule\noalign{}

test/command/8638.md

@@ -7,7 +7,7 @@
 | oranges | 4.25  |
 ^D
 \begin{frame}
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}lr@{}}
 \toprule\noalign{}
 fruit & price \\

test/command/9350.md

@@ -2,7 +2,7 @@
 % pandoc -f html -t latex
 <table><tbody><tr></tr></tbody></table>
 ^D
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}l@{}}
 \toprule\noalign{}
 \endhead

test/tables.latex

@@ -19,7 +19,7 @@ Right & Left & Center & Default \\
 
 Simple table without caption:
 
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}rlcl@{}}
 \toprule\noalign{}
 Right & Left & Center & Default \\
@@ -92,7 +92,7 @@ Second & row & 5.0 & Here's another one. Note the blank line between rows. \\
 
 Multiline table without caption:
 
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}
   >{\centering\arraybackslash}p{(\linewidth - 6\tabcolsep) * \real{0.1500}}
   >{\raggedright\arraybackslash}p{(\linewidth - 6\tabcolsep) * \real{0.1375}}
@@ -119,7 +119,7 @@ Second & row & 5.0 & Here's another one. Note the blank line between rows. \\
 
 Table without column headers:
 
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}rlcr@{}}
 \toprule\noalign{}
 \endhead
@@ -133,7 +133,7 @@ Table without column headers:
 
 Multiline table without column headers:
 
-{\def\LTcaptype{} % do not increment counter
+{\def\LTcaptype{none} % do not increment counter
 \begin{longtable}[]{@{}
   >{\centering\arraybackslash}p{(\linewidth - 6\tabcolsep) * \real{0.1500}}
   >{\raggedright\arraybackslash}p{(\linewidth - 6\tabcolsep) * \real{0.1375}}