[riscv-port-jdk11u:riscv-port] RFR: 8339741: RISC-V: C ABI breakage for integer on stack

[Dingli Zhang]

Hi all, 

Please review this backport to riscv-port-jdk11u.

Backport of [JDK-8339741](https://bugs.openjdk.org/browse/JDK-8339741).

The original patch cannot be directly applied because jdk11u has no [JDK-8294100](https://bugs.openjdk.org/browse/JDK-8294100).

Testing:
- Tier1 passed without new failure on lp4a (release).
- New jtreg test: test/hotspot/jtreg/compiler/calls/TestManyArgs.java

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Commit messages:
 - 8339741: RISC-V: C ABI breakage for integer on stack

Changes: https://git.openjdk.org/riscv-port-jdk11u/pull/35/files
  Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk11u&pr=35&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339741
  Stats: 156 lines in 4 files changed: 150 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/riscv-port-jdk11u/pull/35.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk11u.git pull/35/head:pull/35

PR: https://git.openjdk.org/riscv-port-jdk11u/pull/35