Enhance security during the build process:
* The '-fstack-protector' flag enables stack protection for preventing
buffer overflow vulnerabilities. If an attempt is made to overflow the
buffer, the program will terminate, thus protecting the integrity of
the stack.
* The '-Wl,-z,relro,-z,now' linker flag enables Read-only Relocations
(RELRO), a feature that helps harden the binary against certain types
of exploits, particularly those that involve overwriting the Global
Offset Table (GOT).
* This flag is only set for Linux builds, due to compatibility issues
with apple-clang.
* The `relro` option makes certain sections of memory read-only after
initialization to prevent them from being overwritten, while `now`
ensures that all dynamic symbols are resolved immediately on program
start, reducing the window of opportunity for attacks.
* use tagged containers for pkg build
* update build images
* continue to build container images in pipeline, but allow
failure (non-block)
* limit travis macos cache
* add vs2019 windows to travis
* remove xcode 9 travis build
* remove clang5/6 from CI and update min version of Clang required in
cmake
* break windows CI build into stages to reduce timeouts
* update datelib
* add if condition to travis builds to allow commit message to limit
builds by platform
The existing platform detection code was derived from the old Beast
library, which was, itself, derived from JUCE.
This commit removes that code and replaces it with the Boost.Predef
library which defines a consistent set of compiler, architecture,
operating system, library, and other version numbers.
For more on Boost.Predef, please see the Boost documentation. The
documentation for the current version as of this writing is at:
https://www.boost.org/doc/libs/1_71_0/doc/html/predef.html
