Bug 1662608 - Set -fcrash-diagnostics-dir in build-clang.py r=froydnj

This will let us get reproducers for compiler self-host assertion failures.

Differential Revision: https://phabricator.services.mozilla.com/D89079

build/build-clang/build-clang.py

@@ -826,6 +826,11 @@ if __name__ == "__main__":
         extra_ldflags = ["-Wl,-syslibroot,%s" % os.getenv("CROSS_SYSROOT"),
                          "-Wl,-dead_strip"]
 
+    upload_dir = os.getenv('UPLOAD_DIR')
+    if assertions and upload_dir:
+        extra_cflags2 += ['-fcrash-diagnostics-dir=%s' % upload_dir]
+        extra_cxxflags2 += ['-fcrash-diagnostics-dir=%s' % upload_dir]
+
     build_one_stage(
         [cc] + extra_cflags,
         [cxx] + extra_cxxflags,

taskcluster/scripts/misc/build-clang.sh

@@ -24,7 +24,7 @@ case "$JSON_CONFIG" in
   export PATH=$PATH:$CROSS_CCTOOLS_PATH/bin
   ;;
 *win64*)
-  UPLOAD_DIR=$ORIGPWD/public/build
+  export UPLOAD_DIR=$ORIGPWD/public/build
   # Set up all the Visual Studio paths.
   . taskcluster/scripts/misc/vs-setup.sh