SIZEOF("Section") and STARTOF("Section") can be known

Fixes #890

include/asm/section.h

@@ -13,6 +13,7 @@
 #include <stdbool.h>
 
 #include "linkdefs.h"
+#include "platform.h" // NONNULL
 
 extern uint8_t fillByte;
 
@@ -76,4 +77,6 @@ void sect_BinaryFileSlice(char const *s, int32_t start_pos, int32_t length);
 void sect_PushSection(void);
 void sect_PopSection(void);
 
+bool sect_IsSizeKnown(struct Section const NONNULL(name));
+
 #endif