libcap: split install into install-shared/install-static

In order to support static only builds, split the install target into
install-shared and install-static targets.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: b/libcap/Makefile
===================================================================
--- a/libcap/Makefile
+++ b/libcap/Makefile
@@ -60,11 +60,17 @@
 cap_text.o: cap_text.c $(USE_GPERF_OUTPUT) $(INCLS)
 	$(CC) $(CFLAGS) $(IPATH) $(INCLUDE_GPERF_OUTPUT) -c $< -o $@
 
-install: all
+install: install-shared install-static
+
+install-common:
 	mkdir -p -m 0755 $(INCDIR)/sys
 	install -m 0644 include/sys/capability.h $(INCDIR)/sys
 	mkdir -p -m 0755 $(LIBDIR)
+
+install-static: install-common
 	install -m 0644 $(STALIBNAME) $(LIBDIR)/$(STALIBNAME)
+
+install-shared: install-common
 	install -m 0755 $(MINLIBNAME) $(LIBDIR)/$(MINLIBNAME)
 	ln -sf $(MINLIBNAME) $(LIBDIR)/$(MAJLIBNAME)
 	ln -sf $(MAJLIBNAME) $(LIBDIR)/$(LIBNAME)