[sanitizer] Mark bootstrap builder as 'clean' (#257)

For #250.

This bots can't catch-up with `clean_obj` requests, but they do clean
build anyway.
Maybe we should do the same for all sanitizer builders, but seems they
are OK as is.

buildbot/osuosl/master/config/builders.py

@@ -1562,6 +1562,7 @@
     ],
     'builddir': "sanitizer-x86_64-linux-bootstrap-asan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1573,6 +1574,7 @@
     ],
     'builddir': "sanitizer-x86_64-linux-bootstrap-msan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1584,6 +1586,7 @@
     ],
     'builddir': "sanitizer-x86_64-linux-bootstrap-ubsan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1630,6 +1633,7 @@
     ],
     'builddir': "sanitizer-aarch64-linux-bootstrap-asan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1641,6 +1645,7 @@
     ],
     'builddir': "sanitizer-aarch64-linux-bootstrap-hwasan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1652,6 +1657,7 @@
     ],
     'builddir': "sanitizer-aarch64-linux-bootstrap-msan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},
 
@@ -1663,6 +1669,7 @@
     ],
     'builddir': "sanitizer-aarch64-linux-bootstrap-ubsan",
     'factory' : SanitizerBuilder.getSanitizerBuildFactory(
+        clean=True,
         extra_depends_on_projects=["mlir", "clang-tools-extra"]
     )},