Add a new buildbot preset to build toolchains which contain the debug version of compilers.

The stdlib is built in release mode.
This new preset should make it easier to debug compiler errors and crashers.

Author: swiftix

utils/build-presets.ini

@@ -755,6 +755,18 @@ darwin-toolchain-name=%(darwin_toolchain_xctoolchain_name)s
 darwin-toolchain-version=%(darwin_toolchain_version)s
 darwin-toolchain-alias=%(darwin_toolchain_alias)s
 
+# Debug version of the compilers, release version of the stdlib.
+[preset: buildbot_osx_package,tools=DA,stdlib=R]
+mixin-preset=buildbot_osx_package
+
+build-subdir=buildbot_osx_debug
+
+release-debuginfo
+assertions
+debug-llvm
+debug-swift
+no-swift-stdlib-assertions
+
 #===------------------------------------------------------------------------===#
 # LLDB build configurations
 #