simplify XScale debug handler installation

Load the XScale debug handler from the read-only data section
instead of from a separate file that can get lost or garbaged.
This eliminates installation and versioning issues, and also
speeds up reset handling a bit.

Plus some minor bits of cleanup related to loading that handler:
comments about just what this handler does, and check fault codes
while writing it into the mini-icache.

The only behavioral changes should be cleaner failure modes after
errors during handler loading, and being a bit faster.

NOTE:  presumes GNU assembly syntax, with ".incbin"; and ELF,
because of the syntax of the ".size" directive.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/Makefile.am

@@ -35,6 +35,7 @@ libtarget_la_SOURCES = \
 	feroceon.c \
 	etb.c \
 	xscale.c \
+	xscale_debug.S \
 	arm_simulator.c \
 	image.c \
 	armv7m.c \
@@ -98,7 +99,6 @@ noinst_HEADERS = \
 	avrt.h
 
 nobase_dist_pkglib_DATA =
-nobase_dist_pkglib_DATA += xscale/debug_handler.bin
 nobase_dist_pkglib_DATA += ecos/at91eb40a.elf
 
 MAINTAINERCLEANFILES = $(srcdir)/Makefile.in