DOS refinements

This allows to use the DOS library trees stored in a user-specified directory.

I have mirrored the needed patches, sources and binaries (the latter
are properly licensed to allow that) in the flashrom wiki, so use those
URLs instead of the original sources.

Corresponding to flashrom svn r1734.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>

Makefile

@@ -39,6 +39,7 @@ CFLAGS  ?= -Os -Wall -Wshadow
 EXPORTDIR ?= .
 AR      ?= ar
 RANLIB  ?= ranlib
+DOSLIBS_BASE ?= ..
 # The following parameter changes the default programmer that will be used if there is no -p/--programmer
 # argument given when running flashrom. The predefined setting does not enable any default so that every
 # user has to declare the programmer he wants to use on every run. The rationale for this to be not set
@@ -99,11 +100,12 @@ endif
 
 ifeq ($(TARGET_OS), DOS)
 EXEC_SUFFIX := .exe
-CPPFLAGS += -I../libgetopt
+CPPFLAGS += -I$(DOSLIBS_BASE)/libgetopt
 # DJGPP has odd uint*_t definitions which cause lots of format string warnings.
 CFLAGS += -Wno-format
 # FIXME Check if we can achieve the same effect with -L../libgetopt -lgetopt
-LIBS += ../libgetopt/libgetopt.a
+LIBS += -lgetopt
+LDFLAGS += -L$(DOSLIBS_BASE)/libgetopt/
 # Bus Pirate, Serprog and PonyProg are not supported under DOS (missing serial support).
 ifeq ($(CONFIG_BUSPIRATE_SPI), yes)
 UNSUPPORTED_FEATURES += CONFIG_BUSPIRATE_SPI=yes
@@ -611,9 +613,9 @@ PCILIBS += -lpciutils -lpci
 PCILIBS += -l$(shell uname -p)
 else
 ifeq ($(TARGET_OS), DOS)
-# FIXME There needs to be a better way to do this
-CPPFLAGS += -I../libpci/include
-PCILIBS += ../libpci/lib/libpci.a
+CPPFLAGS += -I$(DOSLIBS_BASE)/libpci/include
+LDFLAGS += -L$(DOSLIBS_BASE)/libpci/lib/
+PCILIBS += -lpci
 else
 PCILIBS += -lpci
 ifeq ($(TARGET_OS), OpenBSD)