Bug 1329272 - add bracket for sed 4.3 compliance, r=glandium

--HG--
extra : rebase_source : aac991847d3c66a6cfb00b83f88d1ffa27ef9bb0

build/autoconf/icu.m4

@@ -69,7 +69,7 @@ if test -n "$USE_ICU"; then
         fi
     fi
 
-    version=`sed -n 's/^[[:space:]]*#[[:space:]]*define[[:space:]][[:space:]]*U_ICU_VERSION_MAJOR_NUM[[:space:]][[:space:]]*\([0-9][0-9]*\)[[:space:]]*$/\1/p' "$icudir/common/unicode/uvernum.h"`
+    version=`sed -n 's/^[[[:space:]]]*#[[:space:]]*define[[:space:]][[:space:]]*U_ICU_VERSION_MAJOR_NUM[[:space:]][[:space:]]*\([0-9][0-9]*\)[[:space:]]*$/\1/p' "$icudir/common/unicode/uvernum.h"`
     if test x"$version" = x; then
        AC_MSG_ERROR([cannot determine icu version number from uvernum.h header file $lineno])
     fi