Ensure that "lib" is the CMAKE_INSTALL_LIBDIR in pugixml bazel dependency (#1043)

If this is not set on some systems this might default to lib64 leading to bazel build errors like:

output 'external/pugixml/libpugixml/lib/libpugixml.a' was not created

Signed-off-by: Kai-Uwe Hermann <kai-uwe.hermann@pionix.de>

Author: hikinggrass

third-party/bazel/BUILD.pugixml.bazel

@@ -8,6 +8,7 @@ filegroup(
 cmake(
     name = "libpugixml",
     cache_entries = {
+        "CMAKE_INSTALL_LIBDIR": "lib",
     },
     lib_source = "@pugixml//:all_srcs",
     visibility = ["//visibility:public"],