jam: Actually build with optimizations.

This makes a huge difference in rebuilds (e.g. jam HaikuDepot
with nothing to do goes from ~5s -> ~3.5s.)

sys-devel/jam/jam-2.5_2021_10_29.recipe

@@ -15,7 +15,7 @@ HOMEPAGE="http://www.perforce.com/jam/jam.html"
 COPYRIGHT="1993-2003 Christopher Seiwald
 	2005-2021 Haiku, Inc."
 LICENSE="Jam"
-REVISION="1"
+REVISION="2"
 srcGitRev="19aaa7936296ae7f71cd47f0d899c6543b2629b6"
 SOURCE_URI="https://github.com/haiku/buildtools/archive/$srcGitRev.tar.gz"
 CHECKSUM_SHA256="7ea7512d07d51cd006cd427090421cc1602c5484590c49f2431369266a117217"
@@ -47,7 +47,7 @@ defineDebugInfoPackage jam \
 
 BUILD()
 {
-	DEBUG=1 make
+	DEBUG=1 OPTIM=-O2 make
 }
 
 INSTALL()