os: Move Genode::Config into 'config' library

Originally, the convenience utility for accessing a process
configuration came in the form of a header file. But this causes
aliasing problems if multiple compilation units access the config while
the configuration gets dynamically updated. Moving the implementation of
the accessor to the singleton object into a library solves those
problems.

os/src/server/nic_bridge/target.mk

@@ -1,5 +1,5 @@
 TARGET    = nic_bridge
-LIBS      = base net
+LIBS      = base net config
 SRC_CC    = component.cc env.cc mac.cc main.cc nic.cc packet_handler.cc
 
 vpath *.cc $(REP_DIR)/src/server/proxy_arp

os/src/server/nit_fb/target.mk

@@ -1,3 +1,3 @@
 TARGET = nit_fb
 SRC_CC = main.cc
-LIBS   = base
+LIBS   = base config

os/src/server/nitpicker/genode/target.mk

@@ -1,5 +1,5 @@
 TARGET   = nitpicker
-LIBS     = base blit
+LIBS     = base blit config
 SRC_CC   = main.cc \
            view_stack.cc \
            view.cc \

os/src/server/part_blk/target.mk

@@ -1,3 +1,3 @@
 TARGET = part_blk
-LIBS   = base
+LIBS   = base config
 SRC_CC = main.cc back_end.cc

os/src/server/ram_fs/main.cc

@@ -635,7 +635,6 @@ int main(int, char **)
 		Xml_node content = config()->xml_node().sub_node("content");
 		preload_content(*env()->heap(), content, root_dir); }
 	catch (Xml_node::Nonexistent_sub_node) { }
-	catch (Config::Invalid) { }
 
 	static File_system::Root root(ep, sliced_heap, sig_rec, root_dir);
 

os/src/server/ram_fs/target.mk

@@ -1,4 +1,4 @@
 TARGET   = ram_fs
 SRC_CC   = main.cc
-LIBS     = base
+LIBS     = base config
 INC_DIR += $(PRG_DIR)

os/src/server/rom_loopdev/target.mk

@@ -1,3 +1,3 @@
 TARGET = rom_loopdev
 SRC_CC = main.cc
-LIBS   = base
+LIBS   = base config

os/src/server/rom_prefetcher/target.mk

@@ -1,3 +1,3 @@
 TARGET = rom_prefetcher
 SRC_CC = main.cc
-LIBS  += base
+LIBS  += base config

os/src/server/tar_fs/target.mk

@@ -1,4 +1,4 @@
 TARGET   = tar_fs
 SRC_CC   = main.cc
-LIBS     = base
+LIBS     = base config
 INC_DIR += $(PRG_DIR)

os/src/server/tar_rom/target.mk

@@ -1,3 +1,3 @@
 TARGET = tar_rom
 SRC_CC = main.cc
-LIBS   = base
+LIBS   = base config