[BOLT][CMAKE] Use IN_LIST check

Summary:
Address @smeenai feedback https://reviews.llvm.org/D117061#inline-1122106:
>CMake has if(IN_LIST) now, which you can use instead of the string(FIND)

IN_LIST is available since CMake 3.3 released in 2015.

Reviewed By: smeenai

FBD33590959

bolt/CMakeLists.txt

@@ -11,10 +11,8 @@ endif()
 
 set(BOLT_INCLUDE_TESTS OFF)
 if (LLVM_INCLUDE_TESTS)
-  string(FIND "${LLVM_ENABLE_PROJECTS}" "clang" POSITION)
-  if (NOT ${POSITION} EQUAL -1)
-    string(FIND "${LLVM_ENABLE_PROJECTS}" "lld" POSITION)
-    if (NOT ${POSITION} EQUAL -1)
+  if ("clang" IN_LIST LLVM_ENABLE_PROJECTS)
+    if ("lld" IN_LIST LLVM_ENABLE_PROJECTS)
       set(BOLT_INCLUDE_TESTS ON)
     else()
       message(WARNING "Not including BOLT tests since lld is disabled")

bolt/lib/Rewrite/CMakeLists.txt

@@ -12,14 +12,12 @@ set(LLVM_LINK_COMPONENTS
   Support
   )
 
-string(FIND "${LLVM_TARGETS_TO_BUILD}" "AArch64" POSITION)
-if (NOT ${POSITION} EQUAL -1)
+if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
   list(APPEND LLVM_LINK_COMPONENTS BOLTTargetAArch64)
   set(BOLT_AArch64 On)
 endif()
 
-string(FIND "${LLVM_TARGETS_TO_BUILD}" "X86" POSITION)
-if (NOT ${POSITION} EQUAL -1)
+if ("X86" IN_LIST LLVM_TARGETS_TO_BUILD)
   list(APPEND LLVM_LINK_COMPONENTS BOLTTargetX86)
   set(BOLT_X64 On)
 endif()

bolt/lib/Target/CMakeLists.txt

@@ -1,11 +1,9 @@
-string(FIND "${LLVM_TARGETS_TO_BUILD}" "X86" POSITION)
-if (NOT ${POSITION} EQUAL -1)
+if ("X86" IN_LIST LLVM_TARGETS_TO_BUILD)
   message(STATUS "Targeting X86 in llvm-bolt")
   add_subdirectory(X86)
 endif()
 
-string(FIND "${LLVM_TARGETS_TO_BUILD}" "AArch64" POSITION)
-if (NOT ${POSITION} EQUAL -1)
+if ("AArch64" IN_LIST LLVM_TARGETS_TO_BUILD)
   message(STATUS "Targeting AArch64 in llvm-bolt")
   add_subdirectory(AArch64)
 endif()