runtime_loader: Add support for DT_GNU_HASH.

This is an alternative to DT_HASH (SystemV/SVR4 hash tables.) Notably,
it uses a Bloom filter to allow an entire image to be skipped
at once rather than searching the actual symbol hash.

We don't currently build anything with DT_GNU_HASH support.
You can test this by adding -Wl,--hash-style=both to HAIKU_LINKFLAGS.
(It seems to increase image sizes by not too much: libroot goes
from 1347139 to 1367691 bytes (20.55 KB) in my build.)

Change-Id: I4a91276490fcd136db175833ee48b36e06ceed47
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7855
Reviewed-by: waddlesplash <[email protected]>

headers/os/kernel/elf.h

@@ -544,6 +544,8 @@ typedef struct {
 #define DT_PREINIT_ARRAY	32	/* preinitialization array */
 #define DT_PREINIT_ARRAYSZ	33	/* preinitialization array size */
 
+#define	DT_GNU_HASH		0x6ffffef5	/* GNU-style hash table */
+
 #define DT_VERSYM       0x6ffffff0	/* symbol version table */
 #define DT_VERDEF		0x6ffffffc	/* version definition table */
 #define DT_VERDEFNUM	0x6ffffffd	/* number of version definitions */