When building a 32-bit kernel for RBTX4927 with gcc version 4.1.2 
20061115
(prerelease) (Ubuntu 4.1.1-21), I get:
arch/mips/lib/delay.c:24:5: warning: "__SIZEOF_LONG__" is not defined
As a consequence, __delay() always uses the 64-bit "dsubu" instruction.
Replace the check for "__SIZEOF_LONG__ == 4" by "BITS_PER_LONG == 32" to
fix this.
Introduced by commit 
5210edcd527773c227465ad18e416a894966324f [MIPS: Make
__{,n,u}delay declarations match definitions and generic delay.h"]
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Patchwork: https://patchwork.linux-mips.org/patch/4678/
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
 
        "       .set    noreorder                               \n"
        "       .align  3                                       \n"
        "1:     bnez    %0, 1b                                  \n"
-#if __SIZEOF_LONG__ == 4
+#if BITS_PER_LONG == 32
        "       subu    %0, 1                                   \n"
 #else
        "       dsubu   %0, 1                                   \n"