Add meson wrapper to build Zephyr targets

Now zephyr build process can be invoked from meson by running:

- meson setup build
- meson compile -C build openrtx_ttwrplus

TG-553

meson.build

@@ -535,6 +535,13 @@ mod17_opts  = {'sources': mod17_src,
                'dependencies': [codec2_dep],
                'include_directories': mod17_inc}
 
+ttwrplus_opts  = {'sources': ['CMakeLists.txt'],
+                  'c_args': [],
+                  'cpp_args': [],
+                  'link_args' : [],
+                  'dependencies': [codec2_dep],
+                  'include_directories': []}
+
 ##
 ## ---------------------------- Compilation targets ----------------------------
 ##
@@ -580,6 +587,12 @@ targets = [
    'flashable': true,
    'wrap': ' ',
    'load_addr': ' '},
+
+   {'name': 'ttwrplus',
+   'opts': ttwrplus_opts,
+   'flashable': true,
+   'wrap': ' ',
+   'load_addr': ' '},
   ]
 
 radio_tool  = find_program('radio_tool')
@@ -591,10 +604,34 @@ elif build_machine.system() == 'windows'
 endif
 gd77_loader = find_program('scripts/gd-77_firmware_loader.py', required:false, disabler:true)
 dfu_util    = find_program('dfu-util',                         required:false, disabler:true)
+west        = find_program('west',                              required:false, disabler:true)
 
 foreach t : targets
 
   name = 'openrtx_'+t['name']
+
+  # ttwrplus is a Zephyr target, thus we only wrap west
+  if name == 'openrtx_ttwrplus'
+
+      txt = custom_target('Copy CMakeLists.txt',
+                    input : 'CMakeLists.txt',
+                    output :  'CMakeLists.txt',
+                    command : ['cp', '@INPUT@', '@OUTPUT@'],
+                    install : false,
+                    build_by_default : true)
+
+      bin = custom_target(name,
+                          input   : txt,
+                          output  : name+'_bin',
+                          command : [west, 'build', '-b', 'ttwrplus', '-d', '.', '..'])
+
+      custom_target(name+'_flash',
+                    input   : bin,
+                    output  : name+'_flash',
+                    command : [west, 'flash'])
+
+  else
+
     exe  = executable(name, kwargs:t['opts'])
 
     if t['flashable']
@@ -682,6 +719,8 @@ foreach t : targets
       endif
 
     endif
+
+  endif
 endforeach
 
 ##