pe-binary: actually check if PE binary is UEFI binary when determining if UKI

If it's not a UEFI binary, then it's not a UKI.

src/shared/pe-binary.h

@@ -123,6 +123,8 @@ typedef struct _packed_ _IMAGE_SECTION_HEADER {
         le32_t Characteristics;
 } IMAGE_SECTION_HEADER;
 
+#define IMAGE_SUBSYSTEM_EFI_APPLICATION 10
+
 bool pe_header_is_64bit(const PeHeader *h);
 
 #define PE_HEADER_OPTIONAL_FIELD(h, field)                           \