This is similar to what was reverted in 3011911 but this time should use
syntax available even before C++11, tested on Clang with
`-std=c++98 -Wall -pedantic`.
Resizing the vector does the same thing that the loops did, it changes
the size for the vector and initializes it with default-constructed
elements (or 0 or its equivalent for POD types).
Where a specific value is needed, it is set with the second
parameter of resize().
Doing this is not necessary as CMake already looks up the default one
correctly and in fact breaks whenever you have multiple Xcode versions
installed so Xcode is not called Xcode.app.
(And it does not respect the default Xcode set using xcode-select)
The behavior now is to respect CMAKE_OSX_SYSROOT if set by the
user on the command line. If it's not set, try to use the hardcoded
path to the 10.9 SDK if it's present. If not, warn about the fact
that a different SDK is used.
When building on macOS targeting an older version than the version of
the SDK currently used, this prevents accidentally using APIs that are
too new (introduced in macOS versions newer than the deployment target).
Instead use PHYSFS_getPrefDir which does the same than the manual
concatenation done before. The organization name argument is required
but is not used on macOS.
