port for QNX7.1 and QNX8.0

[pkleymonov-qnx]

QNX port of asio lib based on asio-1-29-0. Supported and tested by QNX7.1 and QNX8.0 on x86_64 and aarch64.

The port provides two kind of changes:

1. All build releted stuff is planned under asio/qnx/*
2. All qnx releted fixes in source code may be provided in separate PR.

Chages 1. "asio/qnx/*" consits of:

• build, install/uninstall asio tests "make check"
• install/uninstall asio headers into QNX software development platform (SDP) by "make install/uninstall"
• generate qemu QNX image with integrated asio tests which could be run inside VM.
• generate two QPKG for asio headers and asio tests

Changes 2. consist of:

• adaptation for QNX7.1 and QNX8.0
• added qnx specific handling covered by #if defined(__QNX__)

This scope of changes and additional notes may changed/updated later.

Related issues:

1361

1098

976