boot: add optional EFI SBAT support

Add SBAT support, when -Dsbat-distro value is specified. One can use
-Dsbat-distro=auto for autodetection of all sbat options. Many meson configure
options added to customize SBAT CSV values, but sensible defaults are auto
detected by default. SBAT support is required if shim v15+ is used to load
systemd-boot binary or kernel.efi (Type II BootLoaderSpec).

Fixes #19247

src/basic/macro.h

@@ -18,8 +18,6 @@
 #  define _alloc_(...) __attribute__((__alloc_size__(__VA_ARGS__)))
 #endif
 #define _sentinel_ __attribute__((__sentinel__))
-#define _section_(x) __attribute__((__section__(x)))
-#define _used_ __attribute__((__used__))
 #define _destructor_ __attribute__((__destructor__))
 #define _deprecated_ __attribute__((__deprecated__))
 #define _packed_ __attribute__((__packed__))
@@ -30,7 +28,6 @@
 #define _public_ __attribute__((__visibility__("default")))
 #define _hidden_ __attribute__((__visibility__("hidden")))
 #define _weakref_(x) __attribute__((__weakref__(#x)))
-#define _align_(x) __attribute__((__aligned__(x)))
 #define _alignas_(x) __attribute__((__aligned__(__alignof(x))))
 #define _alignptr_ __attribute__((__aligned__(sizeof(void*))))
 #if __GNUC__ >= 7
@@ -138,9 +135,6 @@
 /* automake test harness */
 #define EXIT_TEST_SKIP 77
 
-#define XSTRINGIFY(x) #x
-#define STRINGIFY(x) XSTRINGIFY(x)
-
 /* builtins */
 #if __SIZEOF_INT__ == 4
 #define BUILTIN_FFS_U32(x) __builtin_ffs(x);