Changes

minidump: Rename some architecture constants
The architecture enum contains two kinds of contstants: the "official"
ones defined by Microsoft, and unofficial constants added by breakpad to
cover the architectures not described by the first ones.
Up until now, there was no big need to differentiate between the two.
However, now that Microsoft has defined 
https://docs.microsoft.com/en-us/windows/win32/api/sysinfoapi/ns-sysinfoapi-system_info 
a constant for ARM64, we have a name clash.
This patch renames all breakpad-defined constants with to include the
prefix
"BP_". This frees up the name "ARM64", which I'll re-introduce with the
new
"official" value in a follow-up patch.
Reviewers: amccarth, clayborg
Subscribers: lldb-commits, llvm-commits
Differential Revision: https://reviews.llvm.org/D69285

LiveIntervals: Split live intervals on multiple dead defs
This is a follow-up to D67448.
Split live intervals with multiple dead defs during the initial 
execution of the live interval analysis, but do it outside of the 
function createAndComputeVirtRegInterval.
Differential Revision: https://reviews.llvm.org/D68666

[ASTImporter] Add support for BuiltinTemplateDecl
Summary: That decl kind is currently not implemented.
BuiltinTemplateDecl is for decls that are hardcoded in the ASTContext,
so we can import them like we do other builtin decls by just taking the
equivalent decl from the target ASTContext.
Reviewers: martong, a.sidorin, shafik
Reviewed By: martong, shafik
Subscribers: rnkovacs, kristina, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D69566

[IR] Allow fast math flags on calls with floating point array type.
Summary: This extends the rules for when a call instruction is deemed to
be an FPMathOperator, which is based on the type of the call (i.e. the
return type of the function being called). Previously we only allowed 
floating-point and vector-of-floating-point types. Now we also allow 
arrays (nested to any depth) of floating-point and 
vector-of-floating-point types.
This was motivated by llpc, the pipeline compiler for AMD GPUs
(https://github.com/GPUOpen-Drivers/llpc). llpc has many math library 
functions that operate on vectors, typically represented as <4 x float>, 
and some that operate on matrices, typically represented as
[4 x <4 x float>], and it's useful to be able to decorate calls to all 
of them with fast math flags.
Reviewers: spatel, wristow, arsenm, hfinkel, aemerson, efriedma,
cameron.mcinally, mcberg2017, jmolloy
Subscribers: wdng, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69161