Tools: add OUTPUT_DIR option to the "check_cppcheck" target

- Add optional `--build-dir` & `--output-dir` arguments to
  "static_check_cppcheck.py".
- Support using `project_source_info.py` without the CWD having
  to be the build-directory.
- Make the script executable.

tools/check_source/static_check_cppcheck.py

@@ -3,10 +3,18 @@
 #
 # SPDX-License-Identifier: GPL-2.0-or-later
 
+"""
+Run CPPCHECK on Blender's source files,
+writing results to a log as well as a summary of all checks.
+
+Existing logs are renamed to ``.old.log`` so they can be compared.
+"""
+
 __all__ = (
     "main",
 )
 
+import argparse
 import project_source_info
 import subprocess
 import sys
@@ -352,9 +360,59 @@ def cppcheck_generate_summary(
             log_summary_fh.write(line)
 
 
+def argparse_create() -> argparse.ArgumentParser:
+
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawTextHelpFormatter,
+    )
+
+    parser.add_argument(
+        "--build-dir",
+        dest="build_dir",
+        metavar='BUILD_DIR',
+        type=str,
+        help=(
+            "The build directory (containing CMakeCache.txt).\n"
+            "\n"
+            "Defaults to the \".\"."
+        ),
+        default=".",
+        required=False,
+    )
+
+    parser.add_argument(
+        "--output-dir",
+        dest="output_dir",
+        metavar='OUTPUT_DIR',
+        type=str,
+        help=(
+            "Specify the directory where CPPCHECK logs will be written to.\n"
+            "Using this may be preferred so the build directory can be cleared\n"
+            "without loosing the result of previous checks.\n"
+            "\n"
+            "Defaults to {BUILD_DIR}/cppcheck/"
+        ),
+        default="",
+        required=False,
+    )
+
+    return parser
+
+
 def main() -> None:
-    cmake_dir = os.path.normpath(os.path.abspath(project_source_info.CMAKE_DIR))
-    cppcheck_dir = os.path.join(cmake_dir, "cppcheck")
+    args = argparse_create().parse_args()
+
+    project_source_info.cmake_dir_set(args.build_dir)
+
+    cppcheck_dir = args.output_dir
+
+    if cppcheck_dir:
+        cppcheck_dir = os.path.normpath(os.path.abspath(cppcheck_dir))
+    else:
+        cppcheck_dir = os.path.join(os.path.normpath(os.path.abspath(project_source_info.CMAKE_DIR)), "cppcheck")
+
+    del args
 
     filepath_output_log = os.path.join(cppcheck_dir, "cppcheck.part.log")
     filepath_output_summary_log = os.path.join(cppcheck_dir, "cppcheck_summary.part.log")