stub: also move magic string in stub into .sdmagic PE section

We already did that for sd-boot, hence do it for sd-stub the same way.

Also, move the __attribute__ stuff to the beginning of the statement,
rather than the middle. Mostly just because we usually put it first for
implementations for identifiers (for prototypes we put it last).

src/boot/efi/boot.c

@@ -25,7 +25,7 @@
 #define TEXT_ATTR_SWAP(c) EFI_TEXT_ATTR(((c) & 0b11110000) >> 4, (c) & 0b1111)
 
 /* magic string to find in the binary image */
-static const char _used_ _section_(".sdmagic") magic[] = "#### LoaderInfo: systemd-boot " GIT_VERSION " ####";
+_used_ _section_(".sdmagic") static const char magic[] = "#### LoaderInfo: systemd-boot " GIT_VERSION " ####";
 
 enum loader_type {
         LOADER_UNDEFINED,

src/boot/efi/stub.c

@@ -14,7 +14,7 @@
 #include "util.h"
 
 /* magic string to find in the binary image */
-static const char __attribute__((used)) magic[] = "#### LoaderInfo: systemd-stub " GIT_VERSION " ####";
+_used_ _section_(".sdmagic") static const char magic[] = "#### LoaderInfo: systemd-stub " GIT_VERSION " ####";
 
 static EFI_STATUS combine_initrd(
                 EFI_PHYSICAL_ADDRESS initrd_base, UINTN initrd_size,