Package and bump premake-core

Treat premake like any other dependency and package it separately, this
makes it much easier to bump it in future by making it easier to track
modifications if any.

Moving it to libraries as it is handled the same as other packages. An
argument could be made to have it in build due to it's special nature.
The issue with that approach would be how to handle clean-workspace.sh.
If we split it out we would need a separate clean-premake.sh script and
if we have it cleaned by clean-workspace we through away the download
and already built binary.

Also bump version to 5.0.0-beta2 and backport patch for macOS fix
instead of the Makefile changes. The same fix is needed for gcc-14
(reported upstream), so add a patch injecting unistd.h for Unixes.

Fixes: #6816
Fixes: #6632
Refs: #6847
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

build/workspaces/update-workspaces.sh

@@ -72,10 +72,7 @@ cd ../premake || die
 premake_command="premake5"
 
 if [ "$with_system_premake5" = "false" ]; then
-	# Build bundled premake
-	MAKE=${MAKE} JOBS=${JOBS} ./build.sh || die "Premake 5 build failed"
-
-	premake_command="premake5/bin/release/premake5"
+	premake_command="../../libraries/source/premake-core/bin/premake5"
 fi
 
 echo