powerpc: Use builtins for fls/flsl

Summary:
There's no need to use the fallback fls() and flsl() libkern functions
when the PowerISA includes instructions that already do the bulk of the
work.  Take advantage of this through the GCC builtins __builtin_clz()
and __builtin_clzl().

Reviewed by:	luporl
Differential Revision:	https://reviews.freebsd.org/D22340

stand/powerpc/kboot/main.c

@@ -31,7 +31,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <fdt_platform.h>
 
-#define _KERNEL
 #include <machine/cpufunc.h>
 #include "bootstrap.h"
 #include "host_syscall.h"

sys/conf/files.powerpc

@@ -88,8 +88,6 @@ libkern/divdi3.c		optional	powerpc | powerpcspe
 libkern/ffs.c			standard
 libkern/ffsl.c			standard
 libkern/ffsll.c			standard
-libkern/fls.c			standard
-libkern/flsl.c			standard
 libkern/flsll.c			standard
 libkern/lshrdi3.c		optional	powerpc | powerpcspe
 libkern/memcmp.c		standard

sys/powerpc/include/cpufunc.h

@@ -212,6 +212,20 @@ get_pcpu(void)
 	return (ret);
 }
 
+#define	HAVE_INLINE_FLS
+static __inline __pure2 int
+fls(int mask)
+{
+	return (mask ? 32 - __builtin_clz(mask) : 0);
+}
+
+#define HAVE_INLINE_FLSL
+static __inline __pure2 int
+flsl(long mask)
+{
+	return (mask ? (8 * sizeof(long) - __builtin_clzl(mask)) : 0);
+}
+
 /* "NOP" operations to signify priorities to the kernel. */
 static __inline void
 nop_prio_vlow(void)