Fix create_dist fail with widevine cdm library

We use fake libwidevinecdm.so is used only for building.
During the packaging, file permission is checked by file type and
extension. but our fake file is just empty file. So, handling it
explicitly.

patches/chrome-installer-linux-common-installer.include.patch

@@ -1,5 +1,5 @@
 diff --git a/chrome/installer/linux/common/installer.include b/chrome/installer/linux/common/installer.include
-index 58b80612445aa0616462805f464bcae0b3ee1c3e..8ee1615b31e93caf6259d91e68b1c856c0ac5a70 100644
+index 58b80612445aa0616462805f464bcae0b3ee1c3e..e0551eed012e437aa1109ae47d40d5fcd52c0650 100644
 --- a/chrome/installer/linux/common/installer.include
 +++ b/chrome/installer/linux/common/installer.include
 @@ -75,6 +75,7 @@ process_template() (
@@ -52,7 +52,7 @@ index 58b80612445aa0616462805f464bcae0b3ee1c3e..8ee1615b31e93caf6259d91e68b1c856
      fi
    fi
    LOGO_RESOURCES_PNG=$(find "${BUILDDIR}/installer/theme/" \
-@@ -381,7 +403,7 @@ stage_install_common() {
+@@ -381,12 +403,14 @@ stage_install_common() {
          exit 1
        fi
        local expected_perms=777
@@ -61,3 +61,10 @@ index 58b80612445aa0616462805f464bcae0b3ee1c3e..8ee1615b31e93caf6259d91e68b1c856
        local expected_perms=4755
      elif [[ "${base_name}" = "nacl_irt_"*".nexe" ]]; then
        local expected_perms=644
+     elif [[ "${file_type}" = *"shell script"* ]]; then
+       local expected_perms=755
++    elif [[ "${base_name}" = "libwidevinecdm.so" ]]; then
++      local expected_perms=${actual_perms}
+     elif [[ "${file_type}" = ELF* ]]; then
+       if [[ "${base_name}" = *".so" ]]; then
+         local expected_perms=${SHLIB_PERMS}