Linux: add the arm for build.sh

As build the linux with arm for chrome, there is an ERROR
for building.

Log:
...
FAILED: chromium-browser-unstable_65.0.3317.0-1_arm.deb
python ../../build/gn_run_binary.py installer/debian/build.sh -a arm -b
. -c unstable -d chromium -o . -s
../../build/linux/debian_stretch_arm-sysroot -t linux

ERROR: Don't know how to build DEBs for 'arm'.

Bug: None

Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Change-Id: I3e5cff16484259e3ace4349aff70cd0e2607cd63
Reviewed-on: https://chromium-review.googlesource.com/867182
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#530056}

AUTHORS

@@ -124,6 +124,7 @@ Bruno Roy <brusi_roy@hotmail.com>
 Bryan Donlan <bdonlan@gmail.com>
 Byoungkwon Ko <gogag2@gmail.com>
 Byungwoo Lee <bw80.lee@samsung.com>
+Caesar Wang <wxt@rock-chips.com>
 Caio Marcelo de Oliveira Filho <caio.de.oliveira.filho@intel.com>
 Caitlin Potter <caitpotter88@gmail.com>
 Calvin Mei <calvimei@amazon.com>

chrome/installer/linux/debian/build.sh

@@ -273,6 +273,9 @@ COMMON_PREDEPS="dpkg (>= 1.14.0)"
 cd "${OUTPUTDIR}"
 
 case "$TARGETARCH" in
+  arm )
+    export ARCHITECTURE="armhf"
+    ;;
   ia32 )
     export ARCHITECTURE="i386"
     ;;

chrome/installer/linux/rpm/build.sh

@@ -250,6 +250,9 @@ export USR_BIN_SYMLINK_NAME="${PACKAGE}-${CHANNEL}"
 cd "${OUTPUTDIR}"
 
 case "$TARGETARCH" in
+  arm )
+    export ARCHITECTURE="armhf"
+    ;;
   ia32 )
     export ARCHITECTURE="i386"
     stage_install_rpm