cpupower: Move library to multiarch directory

Upstream moved it from /usr/lib to /usr/lib64 in 4.15, but neither of
these is correct.

debian/changelog

@@ -7,6 +7,7 @@ linux (4.15~rc5-1~exp1) UNRELEASED; urgency=medium
   * lockdown: Update patchset to 2017-11-10 version
   * lockdown: Update calls to kernel_is_locked_down() in "mtd: Disable slram and
     phram when locked down"
+  * cpupower: Move library to multiarch directory
 
  -- Ben Hutchings <ben@decadent.org.uk>  Tue, 26 Dec 2017 16:25:55 +0000
 

debian/libcpupower-dev.install

@@ -1,2 +1,2 @@
 usr/include/*
-usr/lib/lib*.so
+usr/lib/*/lib*.so

debian/libcpupower1.install

@@ -1 +1 @@
-usr/lib/lib*.so.*
+usr/lib/*/lib*.so.*

debian/rules.d/tools/power/cpupower/Makefile

@@ -8,6 +8,8 @@ MAKE_CPUPOWER += CROSS='$(CROSS_COMPILE)'
 
 MAKE_CPUPOWER += PACKAGE_BUGREPORT='Debian\ \(reportbug\ linux-cpupower\)'
 
+MAKE_CPUPOWER += libdir=/usr/lib/$(DEB_HOST_MULTIARCH)
+
 all:
 	$(MAKE_CPUPOWER) -C $(top_srcdir)/tools/power/cpupower