environment variables work in a similar way for C++ code.

# Go references to C

Within the Go file, C's struct field names that are keywords in Go
can be accessed by prefixing them with an underscore: if x points at a C
struct with a field named "type", x._type accesses the field.
C struct fields that cannot be expressed in Go, such as bit fields
or misaligned data, are omitted in the Go struct, replaced by

The same assembler is used for all target operating systems and architectures.
The GOOS and GOARCH environment variables set the desired target.

Flags:

	-D name[=value]
		Predefine symbol name with an optional simple value.
		Can be repeated to define multiple symbols.
	-I dir1 -I dir2
		Search for #include files in dir1, dir2, etc,
		after consulting $GOROOT/pkg/$GOOS_$GOARCH.
	-S