Various: Fixed obscure crashes on Mac

There were a couple of out-of-range/post-free accesses going on, which caused the Mac
build to crash when optimisations were turned on.

engine/common/hpak.c

@@ -275,6 +275,7 @@ void HPAK_AddLump( qboolean bUseQueue, const char *name, resource_t *pResource,
 		Con_DPrintf( S_ERROR "HPAK_AddLump: %s does not have a valid header.\n", srcname );
 		FS_Close( file_src );
 		FS_Close( file_dst );
+		return;
 	}
 
 	length = FS_FileLength( file_src );
@@ -295,12 +296,12 @@ void HPAK_AddLump( qboolean bUseQueue, const char *name, resource_t *pResource,
 	// load the data
 	srcpak.entries = Z_Malloc( sizeof( hpak_lump_t ) * srcpak.count );
 	FS_Read( file_src, srcpak.entries, sizeof( hpak_lump_t ) * srcpak.count );
-	FS_Close( file_src );
 
 	// check if already exists
 	if( HPAK_FindResource( &srcpak, pResource->rgucMD5_hash, NULL ))
 	{
 		Z_Free( srcpak.entries );
+		FS_Close( file_src );
 		FS_Close( file_dst );
 		FS_Delete( dstname );
 		return;
@@ -350,6 +351,8 @@ void HPAK_AddLump( qboolean bUseQueue, const char *name, resource_t *pResource,
 
 	FS_Seek( file_dst, 0, SEEK_SET );
 	FS_Write( file_dst, &hash_pack_header, sizeof( hpak_header_t ));
+
+	FS_Close( file_src );
 	FS_Close( file_dst );
 
 	FS_Delete( srcname );

engine/common/model.c

@@ -252,7 +252,7 @@ Loads a model into the cache
 model_t *Mod_LoadModel( model_t *mod, qboolean crash )
 {
 	char		tempname[MAX_QPATH];
-	long		length = 0;
+	fs_offset_t		length = 0;
 	qboolean		loaded;
 	byte		*buf;
 	model_info_t	*p;

game_launch/wscript

@@ -29,7 +29,7 @@ def build(bld):
 	bld(
 		source   = source,
 		target   = 'xash3d', # hl.exe
-		features = 'c cprogram',
+		features = 'c cxx cxxprogram',
 		includes = includes,
 		use      = libs,
 		install_path = bld.env.BINDIR,