Disable statx syscall usage on Android prior to 11.0.

Even though the syscall number is defined in kernel headers, the syscall
is blacklisted by seccomp in runtime.

Note that Android 11 also introduces the libc wrapper for statx, so
effectively the library will always use the libc wrapper on Android.

Reported in boostorg#229.

Disable statx syscall usage on Android prior to 11.0.

Even though the syscall number is defined in kernel headers, the syscall
is blacklisted by seccomp in runtime.

Note that Android 11 also introduces the libc wrapper for statx, so
effectively the library will always use the libc wrapper on Android.

Reported in boostorg#229.

Use volatile to make sure globals_retainer is not optimized away.

By using volatile qualifier for the internal member of the globals_retainer
class we ensure the constructor formally has observable behavior, which means
it cannot be optimized away.

Related to boostorg#217.

Check that linking with bcrypt works in has_bcrypt config test.

This allows to succeed library compilation if BCrypt API is
available in headers but the library is not.

Added a workaround for Linux headers older than 2.6.19.

linux/magic.h was introduced in Linux kernel 2.6.19, building Boost.Filesystem
with older kernel headers would fail because of this. Only include the header
when it is found and fallback to our local constant definitions when it's not.

Added explicit initializer for path locale deleter to work around cla…

…ng-3.7 bug.

clang-3.7 and possibly other versions require an explicit initializer for
global constant objects, even if they are default-constructible.

Check file status for status_error in create_directories.

create_directories used to ignore errors returned by status()
calls issued internally. The operation would likely fail anyway,
but the error codes returned by create_directories would be incorrect.
Also, it is better to terminate the operation as early as possible
when an error is encountered.

Reported in boostorg#182.

Fixed an exception being thrown by path::remove_filename if the path …

…is "////".

Also added tests verifying the case.

Fixes boostorg#176.

Create symlinks in the test directory in the operations tests.

This should resolve spurious test failures due to multiple test instances
interfering with each other by creating and deleting the same symlink.

On OpenBSD 4.4 and newer, use statvfs to obtain filesystem space info.

Closes boostorg#162.