libbe_build: Fix the new "network" Jamfile.

Was introduced in fa2dd9c45f, but was
causing weird problems (leaving stray '.o's around the tree.) The problem
was that it didn't have a space before the semicolon on the "SubDir" line,
which also ate the following UseHeaders directive, which also meant
that running "jam" inside a subdirectory was broken between that commit
and this one.

src/build/libbe/network/Jamfile

@@ -1,6 +1,5 @@
-SubDir HAIKU_TOP src build libbe network;
+SubDir HAIKU_TOP src build libbe network ;
 
-UseHeaders [ FDirName $(HAIKU_TOP) headers build ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) headers os net ] : true ;
 UseHeaders [ FDirName $(HAIKU_TOP) headers private shared ] : true ;