fpc: add support for aarch64-linux

Supported since fpc 3.2.0.

pkgs/development/compilers/fpc/binary.nix

···
         url = "mirror://sourceforge/project/freepascal/Linux/${version}/fpc-${version}-x86_64-linux.tar";
         sha256 = "0gfbwjvjqlx0562ayyl08khagslrws758al2yhbi4bz5rzk554ni";
       }
+    else if stdenv.hostPlatform.system == "aarch64-linux" then
+      fetchurl {
+        url = "mirror://sourceforge/project/freepascal/Linux/${version}/fpc-${version}.aarch64-linux.tar";
+        sha256 = "1h481ngg3m8nlsg9mw7rr1bn2c4sj4wzqny9bxyq3xvcral12r71";
+      }
     else throw "Not supported on ${stdenv.hostPlatform.system}.";
 
   builder = ./binary-builder.sh;

pkgs/development/compilers/fpc/mark-paths.patch

···
 diff --git a/fpcsrc/compiler/systems/t_linux.pas b/fpcsrc/compiler/systems/t_linux.pas
-index a7398fb9..a1e41ecb 100644
+index a7398fb9..8e46fec0 100644
 --- a/fpcsrc/compiler/systems/t_linux.pas
 +++ b/fpcsrc/compiler/systems/t_linux.pas
 @@ -135,13 +135,13 @@ begin
···
  {$else powerpc64}
        LibrarySearchPath.AddLibraryPath(sysrootpath,'=/lib;=/usr/lib;=/usr/X11R6/lib',true);
  {$endif powerpc64}
+@@ -164,7 +164,7 @@ begin
+       LibrarySearchPath.AddLibraryPath(sysrootpath,'=/usr/lib/i386-linux-gnu',true);
+ {$endif i386}
+ {$ifdef aarch64}
+-      LibrarySearchPath.AddLibraryPath(sysrootpath,'=/usr/lib/aarch64-linux-gnu',true);
++      LibrarySearchPath.AddLibraryPath(sysrootpath,'=@syslibpath@',true);
+ {$endif aarch64}
+ {$ifdef powerpc}
+       LibrarySearchPath.AddLibraryPath(sysrootpath,'=/usr/lib/powerpc-linux-gnu',true);
 @@ -185,53 +185,53 @@ begin
  end;