[BOLT][NFC] Clean up the outdated option --write-dwp in doc (#166150)

Since the "--write-dwp" option has been removed in
[PR](#100771), this patch also
cleans up the corresponding document and test to avoid misleading
issues.

Author: Jinjie-Huang

bolt/docs/CommandLineArgumentReference.md

@@ -381,11 +381,6 @@
 
   Set verbosity level for diagnostic output
 
-- `--write-dwp`
-
-  Output a single dwarf package file (dwp) instead of multiple non-relocatable
-  dwarf object files (dwo).
-
 ### BOLT optimization options:
 
 - `--align-blocks`

bolt/test/X86/dwarf4-ftypes-dwp-input-dwp-output.test

@@ -1,4 +1,4 @@
-# UNSUPPORTED: true
+# REQUIRES: system-linux
 ; RUN: rm -rf %t
 ; RUN: mkdir %t
 ; RUN: cd %t
@@ -8,7 +8,8 @@
 ; RUN: llvm-dwp -e main.exe -o main.exe.dwp
 ; RUN: llvm-dwarfdump --show-form --verbose --debug-types main.exe.dwp | FileCheck -check-prefix=PRE-BOLT %s
 ; RUN: llvm-dwarfdump --show-form --verbose --debug-tu-index main.exe.dwp | FileCheck -check-prefix=PRE-BOLT-DWP-TU-INDEX %s
-; RUN: llvm-bolt main.exe -o main.exe.bolt --update-debug-sections --write-dwp
+; RUN: llvm-bolt main.exe -o main.exe.bolt --update-debug-sections
+; RUN: llvm-dwp -e main.exe.bolt -o main.exe.bolt.dwp
 ; RUN: llvm-dwarfdump --show-form --verbose --debug-types main.exe.bolt.dwp | FileCheck -check-prefix=BOLT %s
 ; RUN: llvm-dwarfdump --show-form --verbose --debug-tu-index main.exe.bolt.dwp | FileCheck -check-prefix=BOLT-DWP-TU-INDEX %s