Redo pkg-config handling with library collecting

pkg-config only handled PKG_CONFIG_SYSROOT_DIR as the stage dir
providing many issues when using packages from installdir for a part
and also build-packages from the host.

For a full implementation, elf dependency tracking from the host
to the snap is also implemented here

LP: #1549570

Signed-off-by: Sergio Schvezov <sergio.schvezov@ubuntu.com>

.travis.yml

@@ -31,7 +31,7 @@ before_script:
   - sudo lxc config device add xenial /dev/sda1 disk source=$(pwd) path=$(pwd)
   # Install the snapcraft dependencies.
   - sudo lxc exec xenial -- apt-get update
-  - sudo lxc exec xenial -- apt-get install -y lxd pyflakes python-flake8 python3.5 python3-apt python3-docopt python3-coverage python3-fixtures python3-flake8 python3-jsonschema python3-mccabe python3-mock python3-pep8 python3-pexpect python3-pip python3-requests python3-requests-oauthlib python3-responses python3-ssoclient python3-testscenarios python3-testtools python3-xdg python3-yaml python3-lxml squashfs-tools python3-progressbar python3-requests-toolbelt python3-petname
+  - sudo lxc exec xenial -- apt-get install -y lxd pyflakes python-flake8 python3.5 python3-apt python3-magic python3-docopt python3-coverage python3-fixtures python3-flake8 python3-jsonschema python3-mccabe python3-mock python3-pep8 python3-pexpect python3-pip python3-requests python3-requests-oauthlib python3-responses python3-ssoclient python3-testscenarios python3-testtools python3-xdg python3-yaml python3-lxml squashfs-tools python3-progressbar python3-requests-toolbelt python3-petname
   - sudo lxc exec xenial -- usermod ubuntu -a -G lxd
 script:
   - sudo -E lxc exec xenial -- su - ubuntu -c "cd $(pwd); TEST_USER_PASSWORD=$TEST_USER_PASSWORD ./runtests.sh $TEST_SUITE"

debian/control

@@ -10,6 +10,7 @@ Build-Depends: debhelper (>= 9),
                python3-fixtures,
                python3-jsonschema,
                python3-lxml,
+               python3-magic,
                python3-petname,
                python3-pkg-resources,
                python3-progressbar,
@@ -33,6 +34,7 @@ Depends: lxd,
          python3-docopt,
          python3-jsonschema,
          python3-lxml,
+         python3-magic,
          python3-petname,
          python3-pkg-resources,
          python3-progressbar,

examples/godd/snapcraft.yaml

@@ -14,11 +14,4 @@ parts:
     plugin: go
     source: https://github.com/mvo5/godd
     source-type: git
-    build-packages: [gcc]
-    stage-packages: [libgudev-1.0-dev]
-    snap:
-     - usr/lib/x86_64-linux-gnu/libgudev-1.0.so*
-     - usr/lib/x86_64-linux-gnu/libobject-2.0.so*
-     - usr/lib/x86_64-linux-gnu/libglib-2.0.so*
-     - lib/x86_64-linux-gnu/libglib-2.0.so*
-     - bin/godd*
+    build-packages: [gcc, libgudev-1.0-dev]