meson_cross: Introduce meson cross file for DJGPP/DOS

With `meson setup --cross-file meson_cross/i586_djgpp_dos.txt builddir`
you can build flashrom as DOS executable.

Change-Id: Iabda73942c1e64cd46604c78533982374f78e1a4
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/73439
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

meson_cross/i586_djgpp_dos.txt

@@ -0,0 +1,29 @@
+# This file is for cross compiling flashrom for DOS with DJGPP.
+#
+# Make sure the program names match your toolchain
+#
+# Make sure pkg-config can find your self compiles libpci
+# or add the path of your libpci.pc as 'pkg_config_libdir'
+# under [properies] below.
+
+[binaries]
+c     = 'i586-pc-msdosdjgpp-gcc'
+ar    = 'i586-pc-msdosdjgpp-ar'
+strip = 'i586-pc-msdosdjgpp-strip'
+pkgconfig = 'pkg-config'
+
+[host_machine]
+system     = 'dos'
+cpu_family = 'x86'
+cpu        = 'i586'
+endian     = 'little'
+
+[built-in options]
+c_std = 'gnu99'
+default_library = 'static'
+
+[project options]
+tests = 'disabled'
+ich_descriptors_tool = 'disabled'
+
+[properties]