Automatically expand bitbake variables inside source/scripts.

• delimited bitbake variables in source/scripts will be replaced with the expanded value of that bitbake variable
  • Example: @@sbindir@@ will be replaced with /usr/sbin
• files in FILES_${PN} are expanded automatically, during do_install:append()
• files in SRC_URI are expanded automatically, during do_patch:append()
• any file can be processed with an explict function call inside bitbake recipe

To automatically process files, add inherit bitbake-variable-substitution to recipe.

Alternatively, a more measured approach may be preferred. Especially useful if FILES_${PN} or SRC_URI is trashy/bloated.

To explicitly/manually select files to process:

# inherit helpers class in recipe
inherit bitbake-variable-substitution-helpers

# call function where appropriate
${@bitbake_variables_search_and_sub("${PATH_OR_FILE_TO_PROCESS}", r"${BITBAKE_VAR_SUB_DELIM}", d)}

This layer will remain compatible with the latest YOCTO LTS.