If LLVM isn't installed then fails_with_llvm? is true

This makes sense, I assure you. Fixes Homebrew/homebrew#7458.

1 files changed, 1 insertions, 1 deletions

diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index cd3a5fa49..5ce54e6fc 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -329,7 +329,7 @@ module MacOS extend self
   def llvm_build_version
     # for Xcode 3 on OS X 10.5 this will not exist
     # NOTE may not be true anymore but we can't test
-    if File.exist? "/usr/bin/llvm-gcc"
+    @llvm_build_version ||= if File.exist? "/usr/bin/llvm-gcc"
       `/usr/bin/llvm-gcc -v 2>&1` =~ /LLVM build (\d{4,})/
       $1.to_i
     end