tools/tests: introduce unit tests for domain ID allocator

Introduce some basic infrastructure for doing domain ID allocation unit tests,
and add a few tests that ensure correctness of the domain ID allocator.

Use <xen-tools/bitops.h> and xen/lib/find-next-bit.c in test hardness code.

Adjust find-next-bit.c to be compiled with __XEN_TOOLS__.

Signed-off-by: Denis Mukhin <dmukhin@ford.com>
Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>

tools/include/xen-tools/bitops.h

@@ -12,6 +12,16 @@
 #define BITS_PER_LONG 32
 #endif
 
+#define ffsl(x)       __builtin_ffsl(x)
+
+#define BIT_WORD(nr)  ((nr) / BITS_PER_LONG)
+
+#define BITS_TO_LONGS(bits) \
+    (((bits) + BITS_PER_LONG - 1) / BITS_PER_LONG)
+
+#define DECLARE_BITMAP(name, bits) \
+    unsigned long name[BITS_TO_LONGS(bits)]
+
 #define BITMAP_ENTRY(_nr,_bmap) ((_bmap))[(_nr) / 8]
 #define BITMAP_SHIFT(_nr) ((_nr) % 8)