[CRIU] [PATCH v3 0/4] make: build improvements

[Kinsbursky Stanislav]

This patch set:
1) Moves syscalls-related files to separated directory.
2) Moves pie-related files to separated directory.
3) Rework and dramatically simplifies pie build.
4) Done a small cleanup to generic Makefile.inc

v2:
1) Better patches comments
2) Rename-aware diffs in patches

v3:
1) Fixed parasite build.
2) Fixed blobs deps - %.bin and %.bin.o can now be build in parallel.
3) Updated restorer link: restorer is not linked with util-net.o anymore.