LDC 1.19.0

[kinke]

Glad to announce LDC 1.19:

* Based on D 2.089.1+.
* LLVM upgraded to v9.0.1, incl. experimental AVR backend.
* New experimental prebuilt Android aarch64 package, including 
prebuilt x86_64 libs too. The Android armv7a package newly 
includes prebuilt i686 libs.
* Slight codegen improvements, incl. a breaking extern(D) ABI 
change for Posix x86[_64] targets, and dead branch elimination 
for if statements with constant condition (in the hopes of 
possibly increasing compilation speed).
* Fixed misc. CMake issues with some LLVM 9 configurations.
* Default Posix linker driver is now `cc` instead of `gcc`.
* Windows: Bundled MinGW-based libs upgraded to MinGW-w64 v7.0.0.

Full release log and downloads: 
https://github.com/ldc-developers/ldc/releases/tag/v1.19.0

Thanks to all contributors!