Fix and improve Windows/MinGW/MSYS build

 - Makefile: Use $(OS_ARCH) to add some MinGW-specific workarounds and
   settings, so that a simple "make" is sufficient on MinGW (instead of
   manual Makefile hacking).

 - Explicitly set CC=gcc in the Makefile, otherwise you get an error like
   "cc: command not found" on MinGW.

 - MinGW doesn't have ffs(), use gcc's __builtin_ffs() instead.

 - Add /usr/local/include and /usr/local/lib to CPPFLAGS/LDFLAGS, that's
   where libusb-win32 and libftdi stuff is usually placed on MinGW/MSYS.

 - Disable serprog (no sockets) and all PCI-based programmers (no libpci)
   for now. That leaves dummy, ft2232_spi, and buspirate_spi enabled on
   MinGW per default.

 - serial.c: Use correct type for 'tmp', both on Windows/MinGW (DWORD)
   and POSIX (ssize_t).

Corresponding to flashrom svn r1363.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
diff --git a/Makefile b/Makefile
index 456c6ae..ea61fb0 100644
--- a/Makefile
+++ b/Makefile
@@ -84,6 +84,88 @@
 endif
 endif
 
+ifeq ($(OS_ARCH), MINGW32_NT-5.1)
+# Explicitly set CC = gcc on MinGW, otherwise: "cc: command not found".
+CC = gcc
+# MinGW doesn't have the ffs() function, but we can use gcc's __builtin_ffs().
+CFLAGS += -Dffs=__builtin_ffs
+# libusb-win32/libftdi stuff is usually installed in /usr/local.
+CPPFLAGS += -I/usr/local/include
+LDFLAGS += -L/usr/local/lib
+# Serprog is not supported under Windows/MinGW (missing sockets support).
+ifeq ($(CONFIG_SERPROG), yes)
+UNSUPPORTED_FEATURES += CONFIG_SERPROG=yes
+else
+override CONFIG_SERPROG = no
+endif
+# For now we disable all PCI-based programmers on Windows/MinGW (no libpci).
+ifeq ($(CONFIG_INTERNAL), yes)
+UNSUPPORTED_FEATURES += CONFIG_INTERNAL=yes
+else
+override CONFIG_INTERNAL = no
+endif
+ifeq ($(CONFIG_RAYER_SPI), yes)
+UNSUPPORTED_FEATURES += CONFIG_RAYER_SPI=yes
+else
+override CONFIG_RAYER_SPI = no
+endif
+ifeq ($(CONFIG_NIC3COM), yes)
+UNSUPPORTED_FEATURES += CONFIG_NIC3COM=yes
+else
+override CONFIG_NIC3COM = no
+endif
+ifeq ($(CONFIG_GFXNVIDIA), yes)
+UNSUPPORTED_FEATURES += CONFIG_GFXNVIDIA=yes
+else
+override CONFIG_GFXNVIDIA = no
+endif
+ifeq ($(CONFIG_SATASII), yes)
+UNSUPPORTED_FEATURES += CONFIG_SATASII=yes
+else
+override CONFIG_SATASII = no
+endif
+ifeq ($(CONFIG_ATAHPT), yes)
+UNSUPPORTED_FEATURES += CONFIG_ATAHPT=yes
+else
+override CONFIG_ATAHPT = no
+endif
+ifeq ($(CONFIG_DRKAISER), yes)
+UNSUPPORTED_FEATURES += CONFIG_DRKAISER=yes
+else
+override CONFIG_DRKAISER = no
+endif
+ifeq ($(CONFIG_NICREALTEK), yes)
+UNSUPPORTED_FEATURES += CONFIG_NICREALTEK=yes
+else
+override CONFIG_NICREALTEK = no
+endif
+ifeq ($(CONFIG_NICNATSEMI), yes)
+UNSUPPORTED_FEATURES += CONFIG_NICNATSEMI=yes
+else
+override CONFIG_NICNATSEMI = no
+endif
+ifeq ($(CONFIG_NICINTEL), yes)
+UNSUPPORTED_FEATURES += CONFIG_NICINTEL=yes
+else
+override CONFIG_NICINTEL = no
+endif
+ifeq ($(CONFIG_NICINTEL_SPI), yes)
+UNSUPPORTED_FEATURES += CONFIG_NICINTEL_SPI=yes
+else
+override CONFIG_NICINTEL_SPI = no
+endif
+ifeq ($(CONFIG_OGP_SPI), yes)
+UNSUPPORTED_FEATURES += CONFIG_OGP_SPI=yes
+else
+override CONFIG_OGP_SPI = no
+endif
+ifeq ($(CONFIG_SATAMV), yes)
+UNSUPPORTED_FEATURES += CONFIG_SATAMV=yes
+else
+override CONFIG_SATAMV = no
+endif
+endif
+
 ifeq ($(OS_ARCH), libpayload)
 CC:=CC=i386-elf-gcc lpgcc
 AR:=i386-elf-ar
diff --git a/serial.c b/serial.c
index 37ea422..5cc2fe0 100644
--- a/serial.c
+++ b/serial.c
@@ -192,7 +192,11 @@
 
 int serialport_write(unsigned char *buf, unsigned int writecnt)
 {
-	long tmp = 0;
+#ifdef _WIN32
+	DWORD tmp = 0;
+#else
+	ssize_t tmp = 0;
+#endif
 
 	while (writecnt > 0) {
 #ifdef _WIN32
@@ -215,7 +219,11 @@
 
 int serialport_read(unsigned char *buf, unsigned int readcnt)
 {
-	long tmp = 0;
+#ifdef _WIN32
+	DWORD tmp = 0;
+#else
+	ssize_t tmp = 0;
+#endif
 
 	while (readcnt > 0) {
 #ifdef _WIN32