try to find pcre.h for HAVE_RULES in any case

[DGarry82]

pcre.h may not be available using default system search paths (e.g. during cross-compilation),
thus have to be bootstrapped using CMAKE_STAGING_PREFIX/CMAKE_FIND_ROOT_PATH

[firewave]

Thanks for your contribution.

Please put this in findDependencies.cmake next to the library check and also please bail out if the include was not found.

I wonder if there is find_package() support for PCRE which should be added as well.

[DGarry82]

Please put this in findDependencies.cmake next to the library check and also please bail out if the include was not found.

Done.

I wonder if there is find_package() support for PCRE which should be added as well.

Seems there's still no official PCRE module support in CMake. There are some hand-made FindPCRE.cmake-like files over GitHub, but it's difficult to tell if there's really a point in including any of them here (probably current minimal support using find_library()/find_path() is sufficient).