meson: enable cross compiling

the inital work for this commit was coming from `Mark van der Putten`.
In order to not have more options for this, the idea came up to use
mesons autodetection using PATH.

If a cross file is specified, the binaries are used from the system,
rather than from the intree. (Which means --cross-file has the
dependency of efl on the buildsystem)

Differential Revision: https://phab.enlightenment.org/D7415

data/elementary/objects/meson.build

@@ -34,8 +34,7 @@ endforeach
 custom_target('prefs_compile',
   input: 'test_prefs.epc',
   output: 'test_prefs.epb',
-  command : ['/usr/bin/env', 'EFL_RUN_IN_TREE=1', elm_prefs_cc.full_path(),
-              '@INPUT@', '@OUTPUT@'],
+  command : elm_prefs_cc_exe + ['@INPUT@', '@OUTPUT@'],
     depends : elm_prefs_cc,
     install : true,
     install_dir : join_paths(dir_data, 'elementary', 'objects'),

src/bin/edje/meson.build

@@ -30,9 +30,14 @@ edje_cc = executable('edje_cc',
         link_args : bin_linker_args
 )
 
-env = find_program('env')
-
-edje_cc_exe = [env, 'EFL_RUN_IN_TREE=1', edje_cc.full_path()]
+if meson.is_cross_build()
+  _edje_cc = find_program('edje_cc', native: true)
+  edje_cc_path = _edje_cc.path()
+  edje_cc_exe = [_edje_cc]
+else
+  env = find_program('env', native: true)
+  edje_cc_exe = [env, 'EFL_RUN_IN_TREE=1', edje_cc.full_path()]
+endif
 
 edje_decc_src = [
   'edje_decc.c',

src/bin/eet/meson.build

@@ -1,4 +1,4 @@
-eet_bin = executable('eet',
+_eet_bin = executable('eet',
   'eet_main.c',
   dependencies: [eet],
   install : true
@@ -8,3 +8,9 @@ install_data(['diffeet','vieet'],
   install_mode: 'rwxr-xr-x',
   install_dir : dir_bin
 )
+
+if meson.is_cross_build()
+  eet_bin = find_program('eet', native : true)
+else
+  eet_bin = _eet_bin
+endif

src/bin/elementary/meson.build

@@ -220,6 +220,16 @@ elm_prefs_cc = executable('elm_prefs_cc',
         link_args: '-rdynamic'
 )
 
+if meson.is_cross_build()
+  _elm_prefs_cc = find_program('elm_prefs_cc', native: true)
+  elm_prefs_cc_path = _elm_prefs_cc.path()
+  elm_prefs_cc_exe = [_elm_prefs_cc]
+else
+  env = find_program('env', native: true)
+  elm_prefs_cc_exe = [env, 'EFL_RUN_IN_TREE=1', elm_prefs_cc.full_path()]
+endif
+
+
 elementary_run_src = [
    'run.c'
 ]

src/bin/eolian/meson.build

@@ -21,4 +21,12 @@ eolian_gen_bin = executable('eolian_gen',
 eolian_gen_path = eolian_gen_bin.full_path()
 
 
-eolian_gen = [eolian_gen_bin, '-S']
+if meson.is_cross_build()
+  _eolian_gen_bin = find_program('eolian_gen', native : true)
+  eolian_gen_path = _eolian_gen_bin.path()
+else
+  _eolian_gen_bin = eolian_gen_bin
+  eolian_gen_path = _eolian_gen_bin.full_path()
+endif
+
+eolian_gen = [_eolian_gen_bin, '-S']