[ctx_profile] Pass lib path into test

Fixes build after cfe9deb on
https://lab.llvm.org/buildbot/#/builders/37/builds/34828

Author: vitalybuka

compiler-rt/test/ctx_profile/TestCases/generate-context.cpp

@@ -5,7 +5,7 @@
 // RUN: cp %llvm_src/include/llvm/ProfileData/CtxInstrContextNode.h %t_include/
 //
 // Compile with ctx instrumentation "on". We treat "theRoot" as callgraph root.
-// RUN: %clangxx %s -lclang_rt.ctx_profile -I%t_include -O2 -o %t.bin -mllvm -profile-context-root=theRoot
+// RUN: %clangxx %s %ctxprofilelib -I%t_include -O2 -o %t.bin -mllvm -profile-context-root=theRoot
 //
 // Run the binary, and observe the profile fetch handler's output.
 // RUN: %t.bin | FileCheck %s

compiler-rt/test/ctx_profile/lit.cfg.py

@@ -33,3 +33,10 @@ def get_required_attr(config, attr_name):
 config.substitutions.append(
     ("%clangxx ", " ".join([config.clang] + config.cxx_mode_flags) + " -ldl -lpthread ")
 )
+
+config.substitutions.append(
+    (
+        "%ctxprofilelib",
+        "-L%s -lclang_rt.ctx_profile%s" % (config.compiler_rt_libdir, config.target_suffix)
+    )
+)