[clr-interp] Fix emit of bb end var moves

[BrzVlad]

This code makes the current stack state match the stack state expected by a bblock that we transition to. The code was accidentally offseting from the current stack pointer, rather than from the base of the stack.

Issue observed by @janvorli in some of the code bring up tests with code involving the ternary conditional operator.

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/coreclr/interpreter/compiler.cpp:405

• The use of m_pStackBase instead of m_pStackPointer appears to correctly fix the offset issue. Please ensure that m_pStackBase is always correctly sized and mirrors the expected layout of the stack to avoid any potential runtime issues.

int sVar = m_pStackBase[i].var;