[zorg][PowerPC] Limit number of threads to 256 on ppc64le-sanitizer bot

[Conanap]

Summary

By default all threads available on the machines are being used
by the Buildbot. This patch limits the use of threads to 256.

This patch is reopened from https://reviews.llvm.org/D87330;
depends on D98645.

[gkistanova]

LGTM

buildbot/osuosl/master/config/builders.py

# Sanitizer builders.
     'workernames' : ["ppc64be-sanitizer"],
     'builddir': "sanitizer-ppc64be",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(timeout=1800)},
 
     {'name' : "sanitizer-ppc64le-linux",
     'tags'  : ["sanitizer", "ppc", "ppc64le"],
     'workernames' : ["ppc64le-sanitizer"],
     'builddir': "sanitizer-ppc64le",
-    'factory' : SanitizerBuilder.getSanitizerBuildFactory(timeout=1800)},
+    'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+                    timeout=1800,
+                    extra_configure_args=[
+                       "-CMAKE_ARGS='-DLLVM_LIT_ARGS=-v -j256'"])},
 
     {'name' : "sanitizer-windows",
     'tags'  : ["sanitizer"],
     'workernames' : ["sanitizer-windows"],
     'builddir': "sanitizer-windows",
     'factory' : AnnotatedBuilder.getAnnotatedBuildFactory(
                     script="sanitizer-windows.py",
                     depends_on_projects=["llvm", "clang", "lld", "compiler-rt"])},