Revert r284511 because it caused build failures on many platforms

The problem is that when inline versions of flsl and flsll are not
available, then libkern.h must be included for their declarations
in kernel sources.
The fix would be trivial, but I would like to figure out first if
it even makes sense to use the libkern provided implementations.

Reported by:	bz
Pointyhat to:	avg

sys/cddl/contrib/opensolaris/uts/common/sys/sysmacros.h

@@ -32,13 +32,6 @@
 
 #include <sys/param.h>
 #include <sys/isa_defs.h>
-#ifdef __FreeBSD__
-#ifdef _KERNEL
-#include <machine/cpufunc.h>
-#else
-#include <strings.h>
-#endif
-#endif
 
 #ifdef	__cplusplus
 extern "C" {
@@ -389,9 +382,6 @@ extern unsigned char bcd_to_byte[256];
 static __inline int
 highbit(ulong_t i)
 {
-#ifdef __FreeBSD__
-	return (flsl(i));
-#else
 	register int h = 1;
 
 	if (i == 0)
@@ -417,7 +407,6 @@ highbit(ulong_t i)
 		h += 1;
 	}
 	return (h);
-#endif
 }
 
 /*
@@ -427,9 +416,6 @@ highbit(ulong_t i)
 static __inline int
 highbit64(uint64_t i)
 {
-#ifdef __FreeBSD__
-	return (flsll(i));
-#else
 	int h = 1;
 
 	if (i == 0)
@@ -453,7 +439,6 @@ highbit64(uint64_t i)
 		h += 1;
 	}
 	return (h);
-#endif
 }
 
 #ifdef	__cplusplus