Remove pseudo targets for building shared libs

Thanks to the change "build: support library builds via lib/<libname>",
shared libraries can now be built directly by the build system.

Issue #4599

repos/base-linux/recipes/src/base-linux/content.mk

@@ -10,7 +10,6 @@ content:
 	  mv lib/mk/spec/$$spec/ld-linux.mk lib/mk/spec/$$spec/ld.mk; done;
 	sed -i "/TARGET/s/core-linux/core/"       src/core/linux/target.mk
 	sed -i "s/BOARD.*unknown/BOARD := linux/" lib/mk/core-linux.inc
-	sed -i "s/ld-linux/ld/"                   src/lib/ld/linux/target.mk
 	sed -i "s/linux_timer_drv/timer/"         src/timer/linux/target.mk
 	rm -rf src/initramfs
 

repos/base-linux/src/lib/ld/linux/target.mk

@@ -1,4 +0,0 @@
-TARGET = ld-linux.lib
-LIBS   = ld-linux
-
-BUILD_ARTIFACTS := ld-linux.lib.so