palemoon: Limit build cores count

Building with too many cores may be the cause of the build flakiness with OfBorg.
Upstream says <=32 cores should work fine, let's see if this helps.
https://forum.palemoon.org/viewtopic.php?f=5&t=28480

pkgs/applications/networking/browsers/palemoon/default.nix

@@ -113,6 +113,13 @@ stdenv.mkDerivation rec {
   configurePhase = ''
     runHook preConfigure
 
+    # Too many cores can lead to build flakiness
+    # https://forum.palemoon.org/viewtopic.php?f=5&t=28480
+    export jobs=$(($NIX_BUILD_CORES<=32 ? $NIX_BUILD_CORES : 32))
+    if [ -z "$enableParallelBuilding" ]; then
+      jobs=1
+    fi
+
     export MOZCONFIG=$PWD/mozconfig
     export MOZ_NOSPAM=1
 
@@ -120,7 +127,7 @@ stdenv.mkDerivation rec {
     export gtkversion=${if withGTK3 then "3" else "2"}
     export xlibs=${lib.makeLibraryPath [ xorg.libX11 ]}
     export prefix=$out
-    export mozmakeflags="-j${if enableParallelBuilding then "$NIX_BUILD_CORES" else "1"}"
+    export mozmakeflags="-j$jobs"
     export autoconf=${autoconf213}/bin/autoconf
 
     substituteAll ${./mozconfig} $MOZCONFIG