Use correct libdir for multiarch Debian (#651)

* Use correct libdir for multiarch Debian

Debian multiarch is a little bit complicated, one particularly important
thing is the installation directory for libraries. For multiarch-enabled
packages it should include the "target triple". However, for Debian this
is not your usual target triple, but *normalized* target triple [1].

[1]: https://wiki.debian.org/Multiarch/Tuples

This is not really noticeable on x86_64 but on 32-bit x86 systems
compilers tend to report {i386,i486,i586,i686}-linux-gnu when the
"correct" one is only i386-linux-gnu.

We should use the correct, normalized triplet since that's what dynamic
loader uses. If the library is installed into an incorrect multiarch
subdirectory then it will fail to load.

Instead of asking the compiler, ask dpkg for the multiarch-correct
triplet for the system on which we are building the package. We always
build packages targeting the host system so this is correct approach.

* Avoid Debian/Ubuntu duplication

Optimize distro detection a bit to avoid duplicating code for Debian
and Ubuntu which are currently the same.

Co-authored-by: Dmytro Shapovalov <[email protected]>

Makefile

@@ -623,17 +623,13 @@ RPM_DEPENDENCIES_THEMISPP = --depends "$(RPM_DEV_PACKAGE_NAME) = $(RPM_VERSION)-
 RPM_DEPENDENCIES_JNI += --depends "$(PACKAGE_NAME) >= $(RPM_VERSION)-$(RPM_RELEASE_NUM)"
 RPM_RELEASE_NUM = 1
 
-ifeq ($(shell lsb_release -is 2> /dev/null),Debian)
+OS_NAME := $(shell lsb_release -is 2>/dev/null || printf 'unknown')
+ifeq ($(OS_NAME),$(filter $(OS_NAME),Debian Ubuntu))
 #0.9.4-153-g9915004+jessie_amd64.deb.
 	NAME_SUFFIX = $(VERSION)+$(DEB_CODENAME)_$(DEB_ARCHITECTURE).deb
 	OS_CODENAME = $(shell lsb_release -cs)
-	DEB_LIBDIR := /lib/$(shell $(CC) -dumpmachine)
-else ifeq ($(shell lsb_release -is 2> /dev/null),Ubuntu)
-	NAME_SUFFIX = $(VERSION)+$(DEB_CODENAME)_$(DEB_ARCHITECTURE).deb
-	OS_CODENAME = $(shell lsb_release -cs)
-	DEB_LIBDIR := /lib/$(shell $(CC) -dumpmachine)
-else
-# centos/rpm
+	DEB_LIBDIR := /lib/$(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
+else ifeq ($(OS_NAME),$(filter $(OS_NAME),RedHatEnterpriseServer CentOS))
 	OS_NAME = $(shell cat /etc/os-release | grep -e "^ID=\".*\"" | cut -d'"' -f2)
 	OS_VERSION = $(shell cat /etc/os-release | grep -i version_id|cut -d'"' -f2)
 	ARCHITECTURE = $(shell arch)