target/hexagon: Replace prepare script with meson target

The purpose of the prepare script is to invoke `cpp` to preprocess input
to idef-parser by expanding a few select macros.  On macOS `cpp`
expands into `clang ... -traditional-cpp` which breaks macro
concatenation.  Replace `cpp` with `${compiler} -E`
and replace the script with a meson custom_target.

Signed-off-by: Anton Johansson <anjo@rev.ng>
Reviewed-by: Brian Cain <brian.cain@oss.qualcomm.com>
Signed-off-by: Brian Cain <brian.cain@oss.qualcomm.com>

target/hexagon/idef-parser/prepare

@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-
-#
-#  Copyright(c) 2019-2021 rev.ng Labs Srl. All Rights Reserved.
-#
-#  This program is free software; you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation; either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#  GNU General Public License for more details.
-#
-#  You should have received a copy of the GNU General Public License
-#  along with this program; if not, see <http://www.gnu.org/licenses/>.
-#
-
-set -e
-set -o pipefail
-
-# Run the preprocessor and drop comments
-cpp "$@"

target/hexagon/meson.build

@@ -280,12 +280,13 @@ if idef_parser_enabled and 'hexagon-linux-user' in target_dirs
         command: [python, files('gen_idef_parser_funcs.py'), semantics_generated, '@OUTPUT@'],
     )
 
+    compiler = meson.get_compiler('c').get_id()
     preprocessed_idef_parser_input_generated = custom_target(
         'idef_parser_input.preprocessed.h.inc',
         output: 'idef_parser_input.preprocessed.h.inc',
         input: idef_parser_input_generated,
         depend_files: [idef_parser_dir / 'macros.h.inc'],
-        command: [idef_parser_dir / 'prepare', '@INPUT@', '-I' + idef_parser_dir, '-o', '@OUTPUT@'],
+        command: [compiler, '-x', 'c', '-E', '-I', idef_parser_dir, '-o', '@OUTPUT@', '@INPUT@'],
     )
 
     flex = generator(