elf, uapi: Add type ElfXX_Versym

The type is used by tools/testing/selftests/vDSO/parse_vdso.c.

To be able to build the vDSO selftests without a libc dependency,
add the type to the kernels own UAPI headers. As documented by elf(5).

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/all/20250226-parse_vdso-nolibc-v2-5-28e14e031ed8@linutronix.de

Author: t-8ch

include/uapi/linux/elf.h

@@ -11,6 +11,7 @@ typedef __u16	Elf32_Half;
 typedef __u32	Elf32_Off;
 typedef __s32	Elf32_Sword;
 typedef __u32	Elf32_Word;
+typedef __u16	Elf32_Versym;
 
 /* 64-bit ELF base types. */
 typedef __u64	Elf64_Addr;
@@ -21,6 +22,7 @@ typedef __s32	Elf64_Sword;
 typedef __u32	Elf64_Word;
 typedef __u64	Elf64_Xword;
 typedef __s64	Elf64_Sxword;
+typedef __u16	Elf64_Versym;
 
 /* These constants are for the segment types stored in the image headers */
 #define PT_NULL    0