Allow to exclude each of the external programmer drivers from being compiled in

Example make commandline if you want only internal programmers:
make CONFIG_FT2232SPI=no CONFIG_SERPROG=no CONFIG_NIC3COM=no
CONFIG_SATASII=no CONFIG_DRKAISER=no CONFIG_DUMMY=no

Of course, all of the CONFIG_* symbols can be mixed and matched as
needed. CONFIG_FT2232SPI is special because even if it is enabled, make
will check if the headers are available and skip it otherwise.

Corresponding to flashrom svn r724.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
diff --git a/internal.c b/internal.c
index a3b2ae5..ea12bbc 100644
--- a/internal.c
+++ b/internal.c
@@ -222,8 +222,8 @@
 	}
 }
 
-/* Fallback shutdown() for programmers which don't need special handling */
-int fallback_shutdown(void)
+/* No-op shutdown() for programmers which don't need special handling */
+int noop_shutdown(void)
 {
 	return 0;
 }
@@ -231,16 +231,23 @@
 /* Fallback map() for programmers which don't need special handling */
 void *fallback_map(const char *descr, unsigned long phys_addr, size_t len)
 {
+	/* FIXME: Should return phys_addr. */
 	return 0;
 }
 
-/* Fallback unmap() for programmers which don't need special handling */
+/* No-op/fallback unmap() for programmers which don't need special handling */
 void fallback_unmap(void *virt_addr, size_t len)
 {
 }
 
-/* No-op fallback for drivers not supporting addr/data pair accesses */
-void fallback_chip_writeb(uint8_t val, chipaddr addr)
+/* No-op chip_writeb() for drivers not supporting addr/data pair accesses */
+uint8_t noop_chip_readb(const chipaddr addr)
+{
+	return 0xff;
+}
+
+/* No-op chip_writeb() for drivers not supporting addr/data pair accesses */
+void noop_chip_writeb(uint8_t val, chipaddr addr)
 {
 }