texlive: fix build with clang 16

There are two instances of `main` with an implicit `int` return type.
This is fixed upstream, so this patch is to allow texlive-2022 to build
until texlive-2023 is merged into nixpkgs.

pkgs/tools/typesetting/tex/texlive/bin.nix

@@ -102,6 +102,12 @@ core = stdenv.mkDerivation rec {
     perl
   ];
 
+  patches = [
+    # Fix implicit `int` on `main`, which results in an error when building with clang 16.
+    # This is fixed upstream and can be dropped with the 2023 release.
+    ./fix-implicit-int.patch
+  ];
+
   hardeningDisable = [ "format" ];
 
   preConfigure = ''
@@ -224,6 +230,9 @@ core-big = stdenv.mkDerivation { #TODO: upmendex
       stripLen = 1;
       extraPrefix = "libs/luajit/LuaJIT-src/";
     })
+    # Fix implicit `int` on `main`, which results in an error when building with clang 16.
+    # This is fixed upstream and can be dropped with the 2023 release.
+    ./fix-implicit-int.patch
   ];
 
   hardeningDisable = [ "format" ];

pkgs/tools/typesetting/tex/texlive/fix-implicit-int.patch

@@ -0,0 +1,22 @@
+diff -ur a/utils/m-tx/mtx-src/prepmx.c b/utils/m-tx/mtx-src/prepmx.c
+--- a/utils/m-tx/mtx-src/prepmx.c	2018-04-28 17:56:18.000000000 -0600
++++ b/utils/m-tx/mtx-src/prepmx.c	2023-07-11 15:21:26.351024424 -0600
+@@ -769,6 +769,7 @@
+ }
+ 
+ 
++int
+ main(int argc, Char *argv[])
+ {  /* ---- Main program ------------------------ */
+   PASCAL_MAIN(argc, argv);
+diff -ur a/utils/pmx/pmx-src/libf2c/main.c b/utils/pmx/pmx-src/libf2c/main.c
+--- a/utils/pmx/pmx-src/libf2c/main.c	2016-02-09 22:31:26.000000000 -0700
++++ b/utils/pmx/pmx-src/libf2c/main.c	2023-07-11 15:49:35.043438384 -0600
+@@ -106,6 +106,7 @@
+ #ifdef KR_headers
+ main(argc, argv) int argc; char **argv;
+ #else
++int
+ main(int argc, char **argv)
+ #endif
+ {