Failing to compile nativelib should stop everything

[Duhemm]

Currently, failing the nativelib will just println an error message, but won't stop the whole process, which may still report success:

> tests/run
[info] Updating {file:/Users/martin/Documents/Projects.nosync/Duhemm/scala-native/}tests...
[info] Resolving jline#jline;2.14.3 ...
[info] Done updating.
[info] Compiling 5 Scala sources to /Users/martin/Documents/Projects.nosync/Duhemm/scala-native/unit-tests/target/scala-2.11/classes...
[warn] [0] /main/scala/scala/scalanative/IssuesSuite.scala:264: a pure expression does nothing in statement position; you may be omitting necessary parentheses
[warn] [1] /main/scala/scala/scalanative/IssuesSuite.scala:265: a pure expression does nothing in statement position; you may be omitting necessary parentheses
[warn] [2] unknown:0: there was one deprecation warning; re-run with -deprecation for details
[warn] /main/scala/scala/scalanative/IssuesSuite.scala: 264 [0], 265 [1]
[warn] unknown: 0 [2]
[error] /Users/martin/Documents/Projects.nosync/Duhemm/scala-native/unit-tests/target/scala-2.11/native/lib/statvfs.c:44:1: error: unknown type name 'foobar'
[error] foobar
[error] ^
[error] /Users/martin/Documents/Projects.nosync/Duhemm/scala-native/unit-tests/target/scala-2.11/native/lib/statvfs.c:46:1: error: expected identifier or '('
[error] int scalanative_fstatvfs(int fd, struct scalanative_statvfs *buf) {
[error] ^
[error] 2 errors generated.
Failed to compile native library runtime code.
[info] Linking (1635 ms)
[info] Discovered 2341 classes and 14739 methods
[info] Optimizing (8468 ms)
[info] Generating intermediate code (918 ms)
[info] Produced 53 files
[info] Compiling to native code (2914 ms)
[info] Linking native code (421 ms)
//
// Hundreds of lines
//
* tests.SuiteSuite$
  [ok] expects true
  [ok] does not expect false
  [ok] expects not false
  [ok] does not expect true
  [ok] expects A and throws A
  [ok] expects C and throws C with function
  [ok] expects A and throws B
  [ok] expects A and doesn't throw
[success] Total time: 17 s, completed May 3, 2017 9:51:53 AM

The error in nativeCompileLib is very unlikely to be noticed in this scenario.