meson: use `platform/` as subdir()

Move build instructions for files inside the `platform/` directory to
`platform/meson.build`. This contains instructions to build
`memaccess.c`, the right endian implementation and selecting the right
legacy command line option for the endian.

The `platform/` directory should contain code that abstracts the
underlying platform but is not involved in flashrom logic.

Change-Id: I88044a3f903f316138483dd872a6d95f8686ae69
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/63826
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72332
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/meson.build b/meson.build
index 5365d2c..1311fa0 100644
--- a/meson.build
+++ b/meson.build
@@ -111,6 +111,8 @@
   'writeprotect_ranges.c',
 )
 
+subdir('platform')
+
 host_is_x86 = ['x86', 'x86_64'].contains(host_machine.cpu_family())
 
 need_serial = [
@@ -170,17 +172,6 @@
   add_project_arguments('-DIS_WINDOWS=0', language : 'c')
 endif
 
-srcs += 'platform/memaccess.c'
-
-if host_machine.endian() == 'little'
-  srcs += 'platform/endian_little.c'
-  add_project_arguments('-D__FLASHROM_LITTLE_ENDIAN__=1', language : 'c')
-endif
-if host_machine.endian() == 'big'
-  srcs += 'platform/endian_big.c'
-  add_project_arguments('-D__FLASHROM_BIG_ENDIAN__=1', language : 'c')
-endif
-
 # some programmers require libusb
 if get_option('usb')
   srcs += 'usbdev.c'
diff --git a/platform/meson.build b/platform/meson.build
new file mode 100644
index 0000000..5a74cef
--- /dev/null
+++ b/platform/meson.build
@@ -0,0 +1,11 @@
+srcs += files(
+  ('endian_' + host_machine.endian() + '.c'),
+  'memaccess.c',
+)
+
+if host_machine.endian() == 'little'
+  add_project_arguments('-D__FLASHROM_LITTLE_ENDIAN__=1', language : 'c')
+endif
+if host_machine.endian() == 'big'
+  add_project_arguments('-D__FLASHROM_BIG_ENDIAN__=1', language : 'c')
+endif