util: add IS_POT macro

This macro kinda complements util_is_power_of_two_*, but is implemented
as a macro. This means that it can expand to a constant integral
expression, and thus be used in static_assert.

Because we don't really need the added complexity, this doesn't handle
zero correctly. But that's OK, because the call-sites will.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Reviewed-by: Yonggang Luo <luoyonggang@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16670>

src/util/macros.h

@@ -371,6 +371,9 @@ do {                       \
 /** Align a value to a power of two */
 #define ALIGN_POT(x, pot_align) (((x) + (pot_align) - 1) & ~((pot_align) - 1))
 
+/** Checks is a value is a power of two. Does not handle zero. */
+#define IS_POT(v) (((v) & ((v) - 1)) == 0)
+
 /**
  * Macro for declaring an explicit conversion operator.  Defaults to an
  * implicit conversion if C++11 is not supported.