KZT, fix: Align x86-64 JUMP_SLOT relocation with glibc

[baibaidashixiong]

Summary / 变更说明

Align x86-64 R_X86_64_JUMP_SLOT handling with glibc by writing the
resolved symbol address without adding the RELA addend.

glibc explicitly ignores the addend for this relocation type:
elf_machine_plt_value() returns the symbol value unchanged, and
elf_machine_fixup_plt() writes that value to the relocation slot.

LATX previously added r_addend when applying an immediate JUMP_SLOT
relocation. With a nonzero addend, this could shift a resolved KZT bridge
address to an invalid entry point, as observed with a realloc
relocation in guest libc when running Steam webhelper.

This change also makes immediate binding consistent with LATX's existing
lazy resolver. It applies to the shared x86-64 KZT relocation path and
does not introduce Steam-specific handling.

Reference:
https://github.com/bminor/glibc/blob/master/sysdeps/x86_64/dl-machine.h

Validation / 验证

Validation recorded for this commit:

• Completed the 64-bit build.
• Tested a malloc/realloc/free probe with a nonzero addend injected into
  the realloc JUMP_SLOT relocation:
  • Before the fix: KZT=1 failed.
  • After the fix: KZT=0 and KZT=1 passed.
• Steam webhelper progressed to browser initialization after the fix.

Checklist / 检查项

• I have read CONTRIBUTING.md. / 我已阅读 CONTRIBUTING.md。
• Every commit contains a DCO sign-off (git commit -s). /
  每个提交都包含 DCO 签署（git commit -s）。
• I have included relevant build or test results, or explained why they
  are not applicable. /
  我已提供相关构建或测试结果，或说明了不适用的原因。