wscript: use taskgen counter to solve problem with compiling shared code instead of hardcoding indexes

cl_dll/wscript

@@ -62,5 +62,5 @@ def build(bld):
 		use      = libs,
 		install_path = install_path,
 		subsystem = bld.env.MSVC_SUBSYSTEM,
-		idx      = 1
+		idx      = bld.get_taskgen_count()
 	)

dlls/wscript

@@ -68,5 +68,5 @@ def build(bld):
 		use      = libs,
 		install_path = install_path,
 		subsystem = bld.env.MSVC_SUBSYSTEM,
-		idx      = 2
+		idx      = bld.get_taskgen_count()
 	)

wscript

@@ -13,6 +13,12 @@ top = '.'
 
 Context.Context.line_just = 55 # should fit for everything on 80x26
 
+@Configure.conf
+def get_taskgen_count(self):
+	try: idx = self.tg_idx_count
+	except: idx = 0 # don't set tg_idx_count to not increase counter
+	return idx
+
 def options(opt):
 	grp = opt.add_option_group('Common options')