Install copyright notices into the final package. This makes LLVM MinGW
comply with many of the licenses (which require attribution), and also
makes it easier for users of LLVM MinGW to audit licenses of software
they use.
This includes building universal binaries (for arm64 and x86_64)
and targeting an older minimum deployment target.
(Before 1919720fdd348ca568b235bf3f1357c198eccd15 in llvm-project,
Jan 2022, building lldb's debugserver failed, if building for macOS
for multiple architectures, or for an architecture other than the
current host.)
Printing '<triple>' causes the shell to try to read a file named
triple. One could either quote it, or just remove the angle brackets;
removing the brackets for simplicity.
This simplifies build-mingw-w64.sh. When building on native
windows (where we also provide unprefixed tools, we can't have
the yet incomplete compiler toolchain in $PATH when building
the mingw-w64 tools. (Logically, build-mingw-w64-tools belong
with build-llvm and install-wrappers; using the original system
compiler to build tools that are supposed to run on the current
machine, as opposed to the cross target, like when building the
runtimes.)
Matthew "strager" Glazar