Use POSIX stdout/stderr redirect in configure macro

This PR fixes an issue wherein redirecting stdout and stderr when 
building kernel modules in configure tests relied on a bashism that 
does not work as expected when /bin/sh is not bash.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-By: Richard Laager <[email protected]>
Signed-off-by: Andrew J. Hesford <[email protected]>
Closes #9990 
Closes #9998

Author: ahesford

config/kernel.m4

@@ -566,7 +566,7 @@ AC_DEFUN([ZFS_LINUX_COMPILE], [
 	AC_TRY_COMMAND([
 	    KBUILD_MODPOST_NOFINAL="$5" KBUILD_MODPOST_WARN="$6"
 	    make modules -k -j$TEST_JOBS -C $LINUX_OBJ $ARCH_UM
-	    M=$PWD/$1 &>$1/build.log])
+	    M=$PWD/$1 >$1/build.log 2>&1])
 	AS_IF([AC_TRY_COMMAND([$2])], [$3], [$4])
 ])