message: feaf(makefile) Add the `HAS_<compiler>` variables.
diff: @@ -105,6 +105,10 @@ endif
  #
  #####
  +HAS_CRANELIFT := 0
  +HAS_LLVM := 0
  +HAS_SINGLEPASS := 0
  +
  # Which compilers we build. These have dependencies that may not be on the system.
  compilers :=
  @@ -113,6 +117,7 @@ compilers :=
  ##
  compilers += cranelift
  +HAS_CRANELIFT := 1
  ##
  # LLVM
  @@ -137,6 +142,10 @@ else
  endif
  endif
  +ifneq (, $(findstring llvm,$(compilers)))
  + HAS_LLVM := 1
  +endif
  +
  ##
  # Singlepass
  ##
  @@ -147,6 +156,10 @@ ifeq ($(IS_WINDOWS), 0)
  endif
  endif
  +ifneq (, $(findstring singlepass,$(compilers)))
  + HAS_SINGLEPASS := 1
  +endif
  +
  #####
  @@ -163,6 +176,7 @@ compilers_engines :=
  # The Cranelift case.
  ##
  +ifeq ($(HAS_CRANELIFT, 1))
  compilers_engines += cranelift-jit
  ifeq ($(IS_WINDOWS), 0)
  @@ -172,13 +186,13 @@ ifeq ($(IS_WINDOWS), 0)
  endif
  endif
  endif
  +endif
  ##
  # The LLVM case.
  ##
  -# If `compilers` contains `llvm`.
  -ifneq (, $(findstring llvm,$(compilers)))
  +ifeq ($(HAS_LLVM), 1)
  ifeq ($(IS_WINDOWS), 0)
  ifeq ($(IS_AMD64), 1)
  compilers_engines += llvm-jit
  @@ -193,8 +207,7 @@ endif
  # The Singlepass case.
  ##
  -# If `compilers` contains `singlepass`.
  -ifneq (, $(findstring singlepass,$(compilers)))
  +ifeq ($(HAS_SINGLEPASS), 1)
  ifeq ($(IS_WINDOWS), 0)
  if ($(IS_AMD64), 1)
  compilers_engines += singlepass-jit
  