usb gadget: link fixes for serial gadget

Change how the serial gadget driver builds:  don't use
separate compilation, since it works poorly when key parts
are library code (with init sections etc).  Instead be as
close as we can to "gcc --combine ...".
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Makefile

@@ -26,7 +26,7 @@ C_UTILS =	composite.o usbstring.o config.o epautoconf.o
 
 g_zero-objs			:= zero.o f_sourcesink.o f_loopback.o $(C_UTILS)
 g_ether-objs			:= ether.o u_ether.o f_subset.o f_ecm.o $(C_UTILS)
-g_serial-objs			:= serial.o u_serial.o f_acm.o f_serial.o $(C_UTILS)
+g_serial-objs			:= serial.o
 g_midi-objs			:= gmidi.o usbstring.o config.o epautoconf.o
 gadgetfs-objs			:= inode.o
 g_file_storage-objs		:= file_storage.o usbstring.o config.o \

drivers/usb/gadget/serial.c

@@ -30,6 +30,24 @@
 
 /*-------------------------------------------------------------------------*/
 
+/*
+ * Kbuild is not very cooperative with respect to linking separately
+ * compiled library objects into one module.  So for now we won't use
+ * separate compilation ... ensuring init/exit sections work to shrink
+ * the runtime footprint, and giving us at least some parts of what
+ * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
+ */
+#include "composite.c"
+#include "usbstring.c"
+#include "config.c"
+#include "epautoconf.c"
+
+#include "f_acm.c"
+#include "f_serial.c"
+#include "u_serial.c"
+
+/*-------------------------------------------------------------------------*/
+
 /* Thanks to NetChip Technologies for donating this product ID.
 *
 * DO NOT REUSE THESE IDs with a protocol-incompatible driver!!  Ever!!