[clang][cmake] Sanitize CLANG_BOLT values (llvm#126768)

This avoids failing later in the build process.

Author: serge-sans-paille

clang/tools/driver/CMakeLists.txt

@@ -23,10 +23,14 @@ if(CLANG_PLUGIN_SUPPORT)
   set(support_plugins SUPPORT_PLUGINS)
 endif()
 
+set(CLANG_BOLT_ALLOWLIST INSTRUMENT PERF LBR)
 set(CLANG_BOLT OFF CACHE STRING "Apply BOLT optimization to Clang. \
-  May be specified as Instrument or Perf or LBR to use a particular profiling \
+May be specified as one of ${CLANG_BOLT_ALLOWLIST} to use a particular profiling \
   mechanism.")
 string(TOUPPER "${CLANG_BOLT}" CLANG_BOLT)
+if (CLANG_BOLT AND NOT CLANG_BOLT IN_LIST CLANG_BOLT_ALLOWLIST)
+    message(FATAL_ERROR "Specified CLANG_BOLT value '${CLANG_BOLT}' is not one of ${CLANG_BOLT_ALLOWLIST}.")
+endif()
 
 if (CLANG_BOLT AND NOT LLVM_BUILD_INSTRUMENTED)
   set(CLANG_BOLT_DEPS clear-bolt-fdata llvm-bolt llvm-readobj)