A path of "$(SRCROOT)/../../SomeFile.cpp" would lose the fake C:\ prefix
when the ellipses are collapsed, and trigger a non-absolute File
assertion.

Now that VST3 builds are signed before and after manifest generation, it
may be necessary to force-sign in order to overwrite the
previously-applied signature.

To prevent too much disruption to people who have our public projects as
part of their build or testing systems we are temporarily ignoring a
warning about using Xcode 15.

Co-authored-by: Roland Rabien <figbug@gmail.com>

This reverts commit 82377a787a.

Reintegrates changes from cf9fc84669

Similar code was incorrectly removed in
070a6b35e9.

When using CLion to invoke CMake, using a Clang toolchain and Ninja, and
targeting x64, CLion will pass -m64 in CMAKE_C_FLAGS and
CMAKE_CXX_FLAGS. The compilers are passed through to the juceaide build,
but the target arch was not, which meant that the linker attempted to
link x86 libraries, which failed.