Various coverage improvements.

Mostly from extra test cases, but also:

* Move the fgets size < 0 assertion into fgets.

* Use ELF aliases for strtoq/strtouq rather than duplicating code.

* Don't check uname() succeeded, since it can't fail.

Test: treehugger
Change-Id: I2e6b3b88b0a3eb16bd68be68b9bc9f40d8043291
diff --git a/tests/Android.bp b/tests/Android.bp
index 7e6e742..586ef34 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -422,6 +422,7 @@
         "sys_uio_test.cpp",
         "sys_un_test.cpp",
         "sys_vfs_test.cpp",
+        "sys_wait_test.cpp",
         "sys_xattr_test.cpp",
         "system_properties_test.cpp",
         "system_properties_test2.cpp",