Create compat18 branch

tests/cross-compile-i686/main.fmf

@@ -20,3 +20,7 @@ adjust+:
   - enabled: false
     because: "compiler-rt.i686 may not be available in snapshot builds when x86_64 tests are executed"
     when: snapshot is defined
+
+  - enabled: false
+    because: "i686 packages not available for compat"
+    when: compat is defined

tests/main.fmf

@@ -14,7 +14,7 @@ framework: shell
 
 # Always define "test" key and override in adjust or in each specific test
 # metadata if needed.
-test: ./test.sh
+test: "PATH=/usr/lib64/llvm18/bin:$PATH ./test.sh"
 
 # Commonly used keys are initialized to empty.
 require: []
@@ -24,8 +24,8 @@ tag: []
 adjust+:
   # Common requirements when LLVM is not SCL-ized
   - require+:
-      - clang
-      - compiler-rt
+      - clang18
+      - compiler-rt18
     when: collection is not defined
 
   # Requirements for SCL-ized LLVM