build: build libc as object, not kbuild library (lib.a)

The way we build the libc files is not a real library that can be
used as a libc and makes managing the source files a bit
difficult, so lets revert back to building the c function files
like everything else in the system to avoid any confusion.

Change-Id: I4e998e37bc376522fe253c4aefefe7804597f0f2
Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Makefile

@@ -519,7 +519,7 @@ scripts: scripts_basic include/config/auto.conf include/config/tristate.conf
 	$(Q)$(MAKE) $(build)=$(@)
 
 
-core-y     := arch/ kernel/ misc/ net/
+core-y := lib/ arch/ kernel/ misc/ net/
 platform-y  := drivers/
 
 ifneq ($(strip $(PROJECT)),)
@@ -551,14 +551,10 @@ include/config/auto.conf: ;
 endif # $(dot-config)
 
 ifdef CONFIG_MINIMAL_LIBC
-# Objects we will link into the kernel / subdirs we need to visit
-KLIBC_DIR := lib/libc/minimal
-libs-y := $(KLIBC_DIR)/
 ZEPHYRINCLUDE += -I$(srctree)/lib/libc/minimal/include
 endif
 
 ifdef CONFIG_TOOLCHAIN_NEWLIB
-libs-y += lib/libc/newlib/
 ALL_LIBS += c m
 endif
 

lib/Makefile

@@ -0,0 +1 @@
+obj-y := libc/

lib/libc/Makefile

@@ -1,2 +1,2 @@
-libs-$(CONFIG_MINIMAL_LIBC) += minimal/
-libs-$(CONFIG_NEWLIB) += newlib/
+obj-$(CONFIG_MINIMAL_LIBC) += minimal/
+obj-$(CONFIG_NEWLIB) += newlib/

lib/libc/minimal/Makefile

@@ -1,5 +1 @@
-lib-y := source/stdout/fprintf.o
-lib-y += source/stdout/prf.o
-lib-y += source/stdout/sprintf.o
-lib-y += source/stdout/stdout_console.o
-lib-y += source/string/string.o
+obj-y := source/

lib/libc/minimal/source/Makefile

@@ -0,0 +1,2 @@
+obj-y := stdout/
+obj-y += string/

lib/libc/minimal/source/stdout/Makefile

@@ -0,0 +1,2 @@
+
+obj-y = fprintf.o  prf.o  sprintf.o  stdout_console.o

lib/libc/minimal/source/string/Makefile

@@ -0,0 +1 @@
+obj-y := string.o

lib/libc/newlib/Makefile

@@ -1 +1 @@
-lib-y := libc-hooks.o
+obj-y := libc-hooks.o