Set default value deny-warnings for compiler profile to false

Author: WaffleLapkin

src/bootstrap/defaults/bootstrap.compiler.toml

@@ -25,6 +25,8 @@ frame-pointers = true
 # e.g. check that it builds locally and check the baseline behavior of a
 # compiler built from latest `master` commit.
 download-rustc = false
+# Don't fail compilation when there are warnings.
+deny-warnings = false
 
 [llvm]
 # Having this set to true disrupts compiler development workflows for people who use `llvm.download-ci-llvm = true`