GNUInstallDirs provided may be absolute paths, in which case appending
to the install prefix is not correct. We can instead use the provided
CMAKE_INSTALL_FULL_* variables, which are precomputed absolute paths.
https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html
Remove 2.6-isms
Remove 2.8-isms
Bump CMake minimum version to 3.4
Disable some options when used as a subdirectory
Use `CONFIGURE_DEPENDS` with `file(GLOB)` when possible
Backport CMake 3.15's MSVC_RUNTIME_LIBRARY setting.
Set all compile options as generator expressions.
Set all find-package files to be installed to the correct file.
Remove `export(PACKAGE)`, as this has been deprecated.
Remove fat binary support
Remove manual setting of iPhone settings. These should be set by parent
projects.
Remove use of ExternalProject for a local use
Conditionally remove format target unless clang-format is found
