Build bionic unit tests for musl

Modify bionic unit tests that are built for glibc so that they also
build against musl.  They don't all pass though:

With glibc:
 2 SLOW TESTS
 4 TIMEOUT TESTS
313 FAILED TESTS
  YOU HAVE 2 DISABLED TESTS

With musl:
11 SLOW TESTS
11 TIMEOUT TESTS
363 FAILED TESTS
  YOU HAVE 2 DISABLED TESTS

Bug: 190084016
Test: m bionic-unit-tests-glibc with musl
Test: atest bionic-unit-tests-static
Test: atest --host bionic-unit-tests-glibc with glibc
Change-Id: I79b6eab04fed3cc4392450df5eef2579412edfe1
diff --git a/tests/fcntl_test.cpp b/tests/fcntl_test.cpp
index a8a4cc5..d50a438 100644
--- a/tests/fcntl_test.cpp
+++ b/tests/fcntl_test.cpp
@@ -28,6 +28,8 @@
 // Glibc v2.19 doesn't include these in fcntl.h so host builds will fail without.
 #if !defined(FALLOC_FL_PUNCH_HOLE) || !defined(FALLOC_FL_KEEP_SIZE)
 #include <linux/falloc.h>
+#endif
+#if !defined(EXT4_SUPER_MAGIC)
 #include <linux/magic.h>
 #endif