LaTeX template: Update to iftex package (#7073)

Load the iftex package directly rather than via the ifxetex and ifluatex compatibility
wrappers, which have been merged into a single package that is part of the LaTeX core.
The capitalization of the commands has been changed for compatibility with older
versions of TeX Live that have the version of iftex by the Persian TeX Group. This had
been removed in
<https://github.com/jgm/pandoc/commit/2845794c0c31b2ef1f3e6a73bb5b109da4c74f37>
for compatibility with BasicTeX, but that is no longer an issue.

4 files changed, 15 insertions, 15 deletions

diff --git a/test/lhs-test.latex b/test/lhs-test.latex
index 32042b103..fdc344335 100644
--- a/test/lhs-test.latex
+++ b/test/lhs-test.latex
@@ -6,8 +6,8 @@
 ]{article}
 \usepackage{amsmath,amssymb}
 \usepackage{lmodern}
-\usepackage{ifxetex,ifluatex}
-\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
+\usepackage{iftex}
+\ifPDFTeX
   \usepackage[T1]{fontenc}
   \usepackage[utf8]{inputenc}
   \usepackage{textcomp} % provide euro and other symbols
@@ -81,7 +81,7 @@
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
 \setcounter{secnumdepth}{-\maxdimen} % remove section numbering
-\ifluatex
+\ifLuaTeX
   \usepackage{selnolig}  % disable illegal ligatures
 \fi
 
diff --git a/test/lhs-test.latex+lhs b/test/lhs-test.latex+lhs
index 4bc674f4a..f9149ba02 100644
--- a/test/lhs-test.latex+lhs
+++ b/test/lhs-test.latex+lhs
@@ -6,8 +6,8 @@
 ]{article}
 \usepackage{amsmath,amssymb}
 \usepackage{lmodern}
-\usepackage{ifxetex,ifluatex}
-\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
+\usepackage{iftex}
+\ifPDFTeX
   \usepackage[T1]{fontenc}
   \usepackage[utf8]{inputenc}
   \usepackage{textcomp} % provide euro and other symbols
@@ -48,7 +48,7 @@
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
 \setcounter{secnumdepth}{-\maxdimen} % remove section numbering
-\ifluatex
+\ifLuaTeX
   \usepackage{selnolig}  % disable illegal ligatures
 \fi
 
diff --git a/test/writer.latex b/test/writer.latex
index 7fc707b27..abf772df4 100644
--- a/test/writer.latex
+++ b/test/writer.latex
@@ -6,8 +6,8 @@
 ]{article}
 \usepackage{amsmath,amssymb}
 \usepackage{lmodern}
-\usepackage{ifxetex,ifluatex}
-\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
+\usepackage{iftex}
+\ifPDFTeX
   \usepackage[T1]{fontenc}
   \usepackage[utf8]{inputenc}
   \usepackage{textcomp} % provide euro and other symbols
@@ -63,7 +63,7 @@
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
 \setcounter{secnumdepth}{-\maxdimen} % remove section numbering
-\ifluatex
+\ifLuaTeX
   \usepackage{selnolig}  % disable illegal ligatures
 \fi
 
diff --git a/test/writers-lang-and-dir.latex b/test/writers-lang-and-dir.latex
index 1172d23a2..d91f77325 100644
--- a/test/writers-lang-and-dir.latex
+++ b/test/writers-lang-and-dir.latex
@@ -7,8 +7,8 @@
 ]{article}
 \usepackage{amsmath,amssymb}
 \usepackage{lmodern}
-\usepackage{ifxetex,ifluatex}
-\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
+\usepackage{iftex}
+\ifPDFTeX
   \usepackage[T1]{fontenc}
   \usepackage[utf8]{inputenc}
   \usepackage{textcomp} % provide euro and other symbols
@@ -45,7 +45,7 @@
 \providecommand{\tightlist}{%
   \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}
 \setcounter{secnumdepth}{-\maxdimen} % remove section numbering
-\ifxetex
+\ifXeTeX
   % Load polyglossia as late as possible: uses bidi with RTL langages (e.g. Hebrew, Arabic)
   \usepackage{polyglossia}
   \setmainlanguage[]{english}
@@ -69,14 +69,14 @@
   \newcommand{\textfrench}[2][]{\foreignlanguage{french}{#2}}
   \newenvironment{french}[2][]{\begin{otherlanguage}{french}}{\end{otherlanguage}}
 \fi
-\ifluatex
+\ifLuaTeX
   \usepackage{selnolig}  % disable illegal ligatures
 \fi
-\ifxetex
+\ifXeTeX
   % Load bidi as late as possible as it modifies e.g. graphicx
   \usepackage{bidi}
 \fi
-\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
+\ifPDFTeX
   \TeXXeTstate=1
   \newcommand{\RL}[1]{\beginR #1\endR}
   \newcommand{\LR}[1]{\beginL #1\endL}