[compiler-rt] [test] Allow expanding lit substitutions recursively

Summary:
This allows using lit substitutions in the `COMPILER_RT_EMULATOR` variable.

(For reference, the ability to expand substitutions recursively has been introduced in https://reviews.llvm.org/D76178.)

Reviewers: phosek, compnerd

Reviewed By: compnerd

Subscribers: dberris, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D83489

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

@@ -23,6 +23,9 @@
     # bash on Windows is usually very slow.
     execute_external = (not sys.platform in ['win32'])
 
+# Allow expanding substitutions that are based on other substitutions
+config.recursiveExpansionLimit = 10
+
 # Setup test format.
 config.test_format = lit.formats.ShTest(execute_external)
 if execute_external: