debug/elf: check if symbol section of 64-bit binary is empty to prevent panic

Originally raised in #62649. The fix
(checking for empty symbols section) was only applied to the 32-bit executables
flow. This commit adds the same fix for the 64-bit executables flow.

Original fix: https://go-review.googlesource.com/c/go/+/528655

Author: adityasaky

src/debug/elf/file.go

@@ -689,6 +689,9 @@ func (f *File) getSymbols64(typ SectionType) ([]Symbol, []byte, error) {
 	if err != nil {
 		return nil, nil, fmt.Errorf("cannot load symbol section: %w", err)
 	}
+	if len(data) == 0 {
+		return nil, nil, errors.New("symbol section is empty")
+	}
 	if len(data)%Sym64Size != 0 {
 		return nil, nil, errors.New("length of symbol section is not a multiple of Sym64Size")
 	}