Added rust support

Rust relies on atomic builtins, which are not implemented in libgcc for
ARM. One is implemented in rust, which is sufficient to get the
current rust test to run.

Issue #1899

repos/base/mk/prg.mk

@@ -19,6 +19,11 @@
 #
 all:
 
+#
+# Tell rust to make an object file instead of anything else
+#
+CC_RUSTC_OPT += --emit obj
+
 #
 # Include common utility functions
 #
@@ -148,6 +153,13 @@ LD_CMD += $(addprefix $(LD_SCRIPT_PREFIX), $(LD_SCRIPTS))
 STATIC_LIBS := $(foreach l,$(FILTER_DEPS),$(LIB_CACHE_DIR)/$l/$l.lib.a)
 STATIC_LIBS := $(sort $(wildcard $(STATIC_LIBS)))
 
+#
+# --whole-archive does not work with rlibs
+#
+RUST_LIBS := $(foreach l,$(FILTER_DEPS),$(LIB_CACHE_DIR)/$l/$l.rlib)
+RUST_LIBS :=  $(sort $(wildcard $(RUST_LIBS))) 
+SHORT_RUST_LIBS := $(subst $(LIB_CACHE_DIR),$$libs,$(RUST_LIBS))
+
 #
 # For hybrid Linux/Genode programs, prevent the linkage Genode's cxx and base
 # library because these functionalities are covered by the glibc or by
@@ -181,7 +193,9 @@ $(LINK_ITEMS) $(TARGET): $(HOST_TOOLS)
 LD_CMD += -Wl,--whole-archive -Wl,--start-group
 LD_CMD += $(SHORT_LINK_ITEMS)
 LD_CMD += $(EXT_OBJECTS)
-LD_CMD += -Wl,--end-group -Wl,--no-whole-archive
+LD_CMD += -Wl,--no-whole-archive
+LD_CMD += $(SHORT_RUST_LIBS)
+LD_CMD += -Wl,--end-group
 
 #
 # Link libgcc to each program