Fixed iOS cross building for old generators

[lasote]

Changelog: Fix: Fixed old CMake build helper to cross-build to iOS when two profiles are specified.
Docs: omit

Close #9202

@memsharded This is limited only to the usage of two profiles, only when build is Macos and host is iOS. Do you think this could still be risky?

[SpaceIm]

I guess all consumers using conan_basic_setup() in their CMakeLists want:

                self.definitions["CMAKE_FIND_ROOT_PATH_MODE_INCLUDE"] = "BOTH"
                self.definitions["CMAKE_FIND_ROOT_PATH_MODE_LIBRARY"] = "BOTH"
                self.definitions["CMAKE_FIND_ROOT_PATH_MODE_PACKAGE"] = "BOTH"

If it is set to ONLY by default, it breaks all the logic of this generator.

I mean, not only iOS needs to ensure BOTH for these variables (usually it's BOTH by default, but not if CMAKE_SYSTEM_NAME is iOS and also tvOS and watchOS I think).

[memsharded]

I don't see the new toolchain setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE, am I missing something? Why this feature in the legacy generators but not the new ones?

[SpaceIm]

I don't see the new toolchain setting CMAKE_FIND_ROOT_PATH_MODE_INCLUDE, am I missing something? Why this feature in the legacy generators but not the new ones?

find_package() doesn't need CMAKE_FIND_ROOT_PATH_MODE_PACKAGE BOTH in CMakeDeps (see #9202 (comment), but it could be replaced by CMAKE_FIND_ROOT_PATH_MODE_PACKAGE BOTH instead).
find_library(), find_path() and find_file() would also need #9427, CMAKE_FIND_ROOT_PATH_MODE_* BOTH is not sufficient.