Remove libworkcache

This was only ever used by rustpkg and is very unmaintained.

[breaking-change]

Author: sfackler

mk/crates.mk

@@ -51,7 +51,7 @@
 
 TARGET_CRATES := libc std green rustuv native flate arena glob term semver \
                  uuid serialize sync getopts collections num test time rand \
-		 workcache url log regex graphviz core rlibc alloc debug
+                 url log regex graphviz core rlibc alloc debug
 HOST_CRATES := syntax rustc rustdoc fourcc hexfloat regex_macros fmt_macros
 CRATES := $(TARGET_CRATES) $(HOST_CRATES)
 TOOLS := compiletest rustdoc rustc
@@ -88,7 +88,6 @@ DEPS_test := std collections getopts serialize term time regex
 DEPS_time := std serialize sync
 DEPS_rand := core
 DEPS_url := std collections
-DEPS_workcache := std serialize collections log
 DEPS_log := std sync
 DEPS_regex := std collections
 DEPS_regex_macros = syntax std regex