Changed local build target for library and linker files.

- The library files are now being built into the lib subdirectory of the
  source.
- The linker files for each library are being copied into the lib source
  subdirectory.

Motivation: The relative locations of files in the source directory after make
are now the same as after make install now. This makes it easier to
reuse examples with their makefiles outside of the libopencm3
sourcecode directory.

Makefile

@@ -25,6 +25,7 @@ LIBDIR		= $(DESTDIR)/$(PREFIX)/lib
 SHAREDIR	= $(DESTDIR)/$(PREFIX)/share/libopencm3/scripts
 INSTALL		= install
 
+SRCLIBDIR = $(shell pwd)/lib
 TARGETS = stm32/f1 stm32/f2 stm32/f4 lpc13xx lpc17xx lpc43xx lm3s 
 
 # Be silent per default, but 'make V=1' will show all compiler calls.
@@ -42,7 +43,7 @@ lib:
 	$(Q)for i in $(addprefix $@/,$(TARGETS)); do \
 		if [ -d $$i ]; then \
 			printf "  BUILD   $$i\n"; \
-			$(MAKE) -C $$i || exit $?; \
+			$(MAKE) -C $$i SRCLIBDIR=$(SRCLIBDIR) || exit $?; \
 		fi; \
 	done
 
@@ -61,11 +62,9 @@ install: lib
 	$(Q)$(INSTALL) -d $(SHAREDIR)
 	$(Q)cp -r include/libopencm3/* $(INCDIR)/libopencm3
 	@printf "  INSTALL libs\n"
-	$(Q)$(INSTALL) -m 0644 lib/*/*/*.a $(LIBDIR)
-	$(Q)$(INSTALL) -m 0644 lib/*/*.a $(LIBDIR)
+	$(Q)$(INSTALL) -m 0644 lib/*.a $(LIBDIR)
 	@printf "  INSTALL ldscripts\n"
-	$(Q)$(INSTALL) -m 0644 lib/*/*/*.ld $(LIBDIR)
-	$(Q)$(INSTALL) -m 0644 lib/*/*.ld $(LIBDIR)
+	$(Q)$(INSTALL) -m 0644 lib/*.ld $(LIBDIR)
 	@printf "  INSTALL scripts\n"
 	$(Q)$(INSTALL) -m 0644 scripts/* $(SHAREDIR)
 
@@ -77,7 +76,7 @@ clean:
 		     $(addsuffix /*/*,$(addprefix examples/,$(TARGETS))); do \
 		if [ -d $$i ]; then \
 			printf "  CLEAN   $$i\n"; \
-			$(MAKE) -C $$i clean || exit $?; \
+			$(MAKE) -C $$i clean SRCLIBDIR=$(SRCLIBDIR) || exit $?; \
 		fi; \
 	done
 	@printf "  CLEAN   doxygen\n"