Linux build: Use sysroot when calculating dependencies

third_party/dpkg-dev/ostable

+# This file contains the table of known operating system names.
+#
+# Architecture names are formed as a combination of the system name
+# (from this table) and CPU name (from cputable) after mapping from
+# the Debian triplet (from triplettable).
+#
+# Column 1 is the Debian name for the system, used to form the system part
+# in the Debian triplet.
+# Column 2 is the GNU name for the system, used to output build and host
+# targets in ‘dpkg-architecture’.
+# Column 3 is an extended regular expression used to match against the
+# system part of the output of the GNU config.guess script.
+#
+# <Debian name>         <GNU name>              <config.guess regex>
+uclibceabi-linux        linux-uclibceabi        linux[^-]*-uclibceabi
+uclibc-linux            linux-uclibc            linux[^-]*-uclibc
+musleabihf-linux        linux-musleabihf        linux[^-]*-musleabihf
+musl-linux              linux-musl              linux[^-]*-musl
+gnueabihf-linux         linux-gnueabihf         linux[^-]*-gnueabihf
+gnueabi-linux           linux-gnueabi           linux[^-]*-gnueabi
+gnuabin32-linux         linux-gnuabin32         linux[^-]*-gnuabin32
+gnuabi64-linux          linux-gnuabi64          linux[^-]*-gnuabi64
+gnuspe-linux            linux-gnuspe            linux[^-]*-gnuspe
+gnux32-linux            linux-gnux32            linux[^-]*-gnux32
+gnulp-linux             linux-gnulp             linux[^-]*-gnulp
+gnu-linux               linux-gnu               linux[^-]*(-gnu.*)?
+gnu-kfreebsd            kfreebsd-gnu            kfreebsd[^-]*(-gnu.*)?
+gnu-knetbsd             knetbsd-gnu             knetbsd[^-]*(-gnu.*)?
+gnu-kopensolaris        kopensolaris-gnu        kopensolaris[^-]*(-gnu.*)?
+gnu-hurd                gnu                     gnu[^-]*
+bsd-darwin              darwin                  darwin[^-]*
+bsd-freebsd             freebsd                 freebsd[^-]*
+bsd-netbsd              netbsd                  netbsd[^-]*
+bsd-openbsd             openbsd                 openbsd[^-]*
+sysv-solaris            solaris                 solaris[^-]*
+uclibceabi-uclinux      uclinux-uclibceabi      uclinux[^-]*-uclibceabi
+uclibc-uclinux          uclinux-uclibc          uclinux[^-]*(-uclibc.*)?
+tos-mint                mint                    mint[^-]*