[MC] Move CompressDebugSections/RelaxELFRelocations from TargetOptions/MCAsmInfo to MCTargetOptions

The convention is for such MC-specific options to reside in
MCTargetOptions. However, CompressDebugSections/RelaxELFRelocations do
not follow the convention: `CompressDebugSections` is defined in both
TargetOptions and MCAsmInfo and there is forwarding complexity.

Move the option to MCTargetOptions and hereby simplify the code. Rename
the misleading RelaxELFRelocations to X86RelaxRelocations. llvm-mc
-relax-relocations and llc -x86-relax-relocations can now be unified.

GitOrigin-RevId: a3319371970b599ef65ef1567c440fbdc3a330f4
diff --git a/test/ELF/weak-undef-got-pie.s b/test/ELF/weak-undef-got-pie.s
index c695ecd..2301400 100644
--- a/test/ELF/weak-undef-got-pie.s
+++ b/test/ELF/weak-undef-got-pie.s
@@ -1,7 +1,7 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64 %p/Inputs/dummy-shared.s -o %t1.o
 # RUN: ld.lld %t1.o -shared -o %t1.so
-# RUN: llvm-mc -filetype=obj -relax-relocations=false -triple=x86_64 %s -o %t.o
+# RUN: llvm-mc -filetype=obj -x86-relax-relocations=false -triple=x86_64 %s -o %t.o
 
 # RUN: ld.lld -pie %t.o %t1.so -o %t
 # RUN: llvm-readobj -r %t | FileCheck --check-prefix=RELOCS %s