Remove unused CMake variable

If was removed in:
03eabb4c57

.drone.yml

@@ -66,7 +66,6 @@ steps:
         -DCMAKE_RULE_MESSAGES=OFF
         -DCMAKE_VERBOSE_MAKEFILE=ON
         -DENABLE_CLANG_PLUGIN=ON
-        -DLLVM_CONFIG_BINARY=/usr/bin/llvm-config
         -DENABLE_FULL_DEBUG=ON
         $CI_WORKSPACE
       - ncpu=$(getconf _NPROCESSORS_ONLN)
@@ -254,6 +253,6 @@ trigger:
 
 ---
 kind: signature
-hmac: 6f4c623111114a6ff0d5f9a63b9616f113051e159c8ba1c312f137768992ecc3
+hmac: 2b33ee4678e119d3c794e8641fbeee97d514b3a027a4538bb1b0dac61e5224cc
 
 ...