Makefile: Don't build or install the libapk and lua module by default

Make the libapk and lua module optional at buildtime and off by default.
This is because enabling libapk requires that mkinitfs also copies the
libapk.so or the initramfs will not work.

To build libapk:

 make LIBAPK=yes

To build lua module (will enable LIBAPK=yes):

 make LUAAPK

To link apk to libapk (will enable LIBAPK=yes):

 make SHARED_LIBAPK=yes

All the above applies to make install target as well.

src/Makefile

@@ -4,23 +4,42 @@ ifeq ($(shell pkg-config --print-errors --exists $(PKGDEPS) || echo fail),fail)
 $(error Build dependencies are not met)
 endif
 
-shlibs-y		+= libapk.so
-libapk.so-objs		:= common.o state.o database.o package.o archive.o \
-			   version.o io.o url.o gunzip.o blob.o hash.o print.o
-
+# lua module
+ifneq ($(LUAAPK),)
+LIBAPK			:= YesPlease
 shlibs-y		+= apk.so
 apk.so-objs		:= lua-apk.o
 CFLAGS_lua-apk.o	:= -DAPK_VERSION=\"$(FULL_VERSION)\"
 LIBS_apk.so		:= -L$(obj) -lapk
+LUA_LIB-y		:= $(obj)/apk.so
+install-LUA_LIB-y	:= $(INSTALLDIR) $(DESTDIR)$(LUA_LIBDIR) \
+			   $(INSTALL) $(LUA_LIB-y) $(DESTDIR)$(LUA_LIBDIR)
+endif
 
 progs-y			+= apk
 apk-objs		:= apk.o add.o del.o fix.o update.o info.o \
 			   search.o upgrade.o cache.o ver.o index.o fetch.o \
 			   audit.o verify.o
 
+libapk.so-objs		:= common.o state.o database.o package.o archive.o \
+			   version.o io.o url.o gunzip.o blob.o hash.o print.o
+
+ifeq ($(SHARED_LIBAPK),)
+apk-objs		+= $(libapk.so-objs)
+else
+LIBAPK			:= YesPlease
+LIBS_apk		:= -lapk
+endif
+
+ifneq ($(LIBAPK),)
+shlibs-y		+= libapk.so
+LIBAPK-y		:= $(obj)/libapk.so
+install-LIBAPK-y	:= $(INSTALLDIR) $(DESTDIR)$(LIBDIR) \
+			   $(INSTALL) $(LIBAPK-y) $(DESTDIR)$(LIBDIR)
+endif
+
 CFLAGS_ALL		+= -D_ATFILE_SOURCE
 CFLAGS_apk.o		:= -DAPK_VERSION=\"$(FULL_VERSION)\"
-LIBS_apk		:= -lapk
 
 progs-$(STATIC)		+= apk.static
 apk.static-objs		:= $(apk-objs)
@@ -32,13 +51,13 @@ LIBS			:= -Wl,--as-needed \
 				$(shell pkg-config --libs $(PKGDEPS)) \
 			   -Wl,--no-as-needed
 
-$(obj)/apk:	$(obj)/libapk.so
+$(obj)/apk:	$(LIBAPK-y)
 
 $(obj)/apk.so:	$(obj)/libapk.so
 
-install: $(obj)/apk $(obj)/libapk.so $(obj)/apk.so
-	$(INSTALLDIR) $(addprefix $(DESTDIR),$(SBINDIR) $(LIBDIR) $(LUA_LIBDIR))
+install: $(obj)/apk $(LIBAPK-y) $(LUA_LIB-y)
+	$(INSTALLDIR) $(DESTDIR)$(SBINDIR)
 	$(INSTALL) $(obj)/apk $(DESTDIR)$(SBINDIR)
-	$(INSTALL) $(obj)/libapk.so $(DESTDIR)$(LIBDIR)
-	$(INSTALL) $(obj)/apk.so $(DESTDIR)$(LUA_LIBDIR)
+	$(install-LIBAPK-y)
+	$(install-LUA_LIB-y)