Allow passing "-vv" to cargo fuzz

It should help to figure out how libFuzzer is built and linked
against, which in turn should be useful in scenarios like
google/oss-fuzz#5867 (comment)

src/options.rs

@@ -72,8 +72,8 @@ pub struct BuildOptions {
  pub debug_assertions: bool,
 
  /// Build target with verbose output from `cargo build`
- #[structopt(short = "v", long = "verbose")]
- pub verbose: bool,
+ #[structopt(short = "v", long = "verbose", parse(from_occurrences))]
+ pub verbose: i32,
 
  #[structopt(long = "no-default-features")]
  /// Build artifacts with default Cargo features disabled
@@ -144,7 +144,7 @@ impl stdfmt::Display for BuildOptions {
  write!(f, " -a")?;
  }
 
- if self.verbose {
+ for _ in 0..self.verbose {
  write!(f, " -v")?;
  }
 
@@ -213,7 +213,7 @@ mod test {
  dev: false,
  release: false,
  debug_assertions: false,
- verbose: false,
+ verbose: 0,
  no_default_features: false,
  all_features: false,
  features: None,
@@ -240,7 +240,7 @@ mod test {
  ..default_opts.clone()
  },
  BuildOptions {
- verbose: true,
+ verbose: 1,
  ..default_opts.clone()
  },
  BuildOptions {

src/project.rs

@@ -140,7 +140,7 @@ impl FuzzProject {
  if !build.dev {
  cmd.arg("--release");
  }
- if build.verbose {
+ for _ in 0..build.verbose {
  cmd.arg("--verbose");
  }
  if build.no_default_features {