CFLAGS, CPPFLAGS, CXXFLAGS, FFLAGS and LDFLAGS may be defined with pseudo
#cgo directives within these comments to tweak the behavior of the C, C++
or Fortran compiler. Values defined in multiple directives are concatenated
together. The directive can include a list of build constraints limiting its
effect to systems satisfying one of the constraints
(see https://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
For example:

		File: []ZipTestFile{
			{
				Name:    "世界",
				Content: []byte{},
				Mode:    0644,
				// Name is valid UTF-8, but format does not have UTF-8 flag set.
				// We don't do UTF-8 detection for multi-byte runes due to
				// false-positives with other encodings (e.g., Shift-JIS).
				// Format says encoding is not UTF-8, so we trust it.
				NonUTF8:  true,

		var prefix string
		switch {
		case format.has(FormatUSTAR | FormatPAX):
			hdr.Format = format
			ustar := tr.blk.toUSTAR()
			prefix = p.parseString(ustar.prefix())

			// For Format detection, check if block is properly formatted since
			// the parser is more liberal than what USTAR actually permits.
			notASCII := func(r rune) bool { return r >= 0x80 }
			if bytes.IndexFunc(tr.blk[:], notASCII) >= 0 {