meson.build: fix linker error on unit tests

Append the sources of the main entrypoint only when defining the build
targets for the executables. This avoids having the symbol for main()
defined twice when building the unit tests.

meson.build

@@ -101,10 +101,10 @@ ui_src_module17 = ['openrtx/src/ui/module17/ui.c',
 ## Selection of main entrypoint
 ##
 if get_option('test') != ''
-  openrtx_src += 'tests/platform/'+get_option('test')+'.c'
+  main_src     = 'tests/platform/'+get_option('test')+'.c'
   openrtx_def += {'RUNNING_TESTSUITE' : ''}
 else
-  openrtx_src += 'openrtx/src/main.c'
+  main_src     = 'openrtx/src/main.c'
 endif
 
 ##
@@ -682,7 +682,14 @@ foreach t : targets
 
   else
 
-    exe  = executable(name, kwargs:t['opts'])
+    target_opts = t['opts']
+    exe = executable(name,
+                     sources             : target_opts['sources'] + main_src,
+                     include_directories : target_opts['include_directories'],
+                     dependencies        : target_opts['dependencies'],
+                     c_args              : target_opts['c_args'],
+                     cpp_args            : target_opts['cpp_args'],
+                     link_args           : target_opts['link_args'])
 
     if t['flashable']
 
@@ -767,7 +774,8 @@ unit_test_opts = {'c_args'             : linux_c_args,
                   'include_directories': linux_inc,
                   'dependencies'       : [sdl_dep, threads_dep, pulse_dep, codec2_dep],
                   'link_args'          : linux_l_args}
-unit_test_src = openrtx_src + linux_src + ui_src_default
+
+unit_test_src = linux_src + ui_src_default
 
 m17_golay_test = executable('m17_golay_test',
                             sources : unit_test_src + ['tests/unit/M17_golay.cpp'],