Add the ability to ignore packages

The previous idea was to use virtual packages in the users configuration
to satisfy dependencies by mapping them to existing installed packages.
Using virtual packages for it doesn't work as expected and trying to make
it work would break other functionalities of virtual packages, like the
version satisfaction checks for `provides` and the ability to replace
virtual packages with real packages. The virtual package functionality
should be used exclusively for virtual packages.

This allows users to specify packages packages that should be ignored.
Ignored packages in dependencies are always satisfied without installing
the package, while updating or installing a package that depends on an
ignored package.

This does NOT ignore the shlib checks, ignoring a package that provides
required shared libraries will abort the transaction as if there was no
package that provides the required shared library.

tests/xbps/libxbps/shell/Kyuafile

@@ -24,3 +24,4 @@ atf_test_program{name="update_itself"}
 atf_test_program{name="cyclic_deps"}
 atf_test_program{name="conflicts"}
 atf_test_program{name="downgrade_hold"}
+atf_test_program{name="ignore"}

tests/xbps/libxbps/shell/Makefile

@@ -7,7 +7,7 @@ TESTSHELL+= replace_test installmode_test obsoletefiles_test
 TESTSHELL+= issue31_test scripts_test incorrect_deps_test
 TESTSHELL+= vpkg_test install_test preserve_files_test configure_test
 TESTSHELL+= update_shlibs update_hold update_repolock cyclic_deps conflicts
-TESTSHELL+= update_itself downgrade_hold
+TESTSHELL+= update_itself downgrade_hold ignore
 EXTRA_FILES = Kyuafile
 
 include $(TOPDIR)/mk/test.mk

tests/xbps/libxbps/shell/ignore.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env atf-sh
+
+atf_test_case install_with_ignored_dep
+
+install_with_ignored_dep_head() {
+	atf_set "descr" "Tests for pkg install: with ignored dependency"
+}
+
+install_with_ignored_dep_body() {
+	mkdir -p repo pkg_A pkg_B
+	cd repo
+	xbps-create -A noarch -n A-1.0_1 -s "A pkg" ../pkg_A
+	atf_check_equal $? 0
+	xbps-create -A noarch -n B-1.0_1 -s "B pkg" ../pkg_B
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+	echo "ignorepkg=B" > ignore.conf
+	out=$(xbps-install -r root -C ignore.conf --repository=$PWD/repo -n A)
+	set -- $out
+	exp="$1 $2 $3 $4"
+	atf_check_equal "$exp" "A-1.0_1 install noarch $PWD/repo"
+	xbps-install -r root -C ignore.conf --repository=$PWD/repo -yd A
+	atf_check_equal $? 0
+	xbps-query -r root A
+	atf_check_equal $? 0
+	xbps-query -r root B
+	atf_check_equal $? 2
+}
+
+atf_test_case update_with_ignored_dep
+
+update_with_ignored_dep_head() {
+	atf_set "descr" "Tests for pkg update: with ignored dependency"
+}
+
+update_with_ignored_dep_body() {
+	mkdir -p repo pkg_A pkg_B
+	cd repo
+	xbps-create -A noarch -n A-1.0_1 -s "A pkg" ../pkg_A
+	atf_check_equal $? 0
+	xbps-create -A noarch -n B-1.0_1 -s "B pkg" ../pkg_B
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+	echo "ignorepkg=B" > ignore.conf
+	xbps-install -r root -C ignore.conf --repository=$PWD/repo -yd A
+	atf_check_equal $? 0
+	cd repo
+	xbps-create -A noarch -n A-1.1_1 -s "A pkg" ../pkg_A
+	atf_check_equal $? 0
+	xbps-rindex -d -a $PWD/*.xbps
+	atf_check_equal $? 0
+	cd ..
+	out=$(xbps-install -r root -C ignore.conf --repository=$PWD/repo -un)
+	set -- $out
+	exp="$1 $2 $3 $4"
+	atf_check_equal "$exp" "A-1.1_1 update noarch $PWD/repo"
+	xbps-install -r root --repository=$PWD/repo -yuvd
+	atf_check_equal $? 0
+	out=$(xbps-query -r root -p pkgver A)
+	atf_check_equal $out A-1.1_1
+}
+
+atf_init_test_cases() {
+	atf_add_test_case install_with_ignored_dep
+	atf_add_test_case update_with_ignored_dep
+}