RFR: 8293844: C2: Verify Location::{oop,normal} types in PhaseOutput::FillLocArray

[Aleksey Shipilev]

I have been debugging a weird issue in C2/deopt, and wanted to have stronger asserts in critical paths. One such place is `PhaseOutput::FillLocArray`, which emits `Location::normal` on unconditional `else` branch. `Location::normal` is described as "Ints, floats, double halves". I think we would be better off verifying the types explicitly. Same goes for `Location::oop`, which we can also verify.

Aside: In fact, I suspect the whole `Regalloc::is_oop` business can go away, and we can rely on reg types to sense if we are dealing with oops here, but that looks like a change with some unexpected effects, so I would like to do that separately, see [JDK-8293845](https://bugs.openjdk.org/browse/JDK-8293845).

Additional testing:
 - [x] Linux x86_64 fastdebug `tier1`
 - [x] Linux x86_64 fastdebug `tier2`
 - [x] Linux x86_32 fastdebug `tier1`
 - [x] Linux x86_32 fastdebug `tier2`

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/10281/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10281&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293844
  Stats: 9 lines in 1 file changed: 8 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10281.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10281/head:pull/10281

PR: https://git.openjdk.org/jdk/pull/10281