Replace assert(true) in tests with actual asserts. Reviewed as https://reviews.llvm.org/D40324

In a17cd7c641c34b6c4bd4845a4d4fb590cb6c238c Marshall added assert(true) to the vector<bool>::size tests, which break on C1XX:

D:\Contest\gl0qojfu.5pe\src\qa\vc\libs\libcxx\upstream\test\std\containers\sequences\vector.bool\size.pass.cpp(62): error C2220: warning treated as error - no 'object' file generated
d:\contest\gl0qojfu.5pe\src\qa\vc\libs\libcxx\upstream\test\std\containers\sequences\vector.bool\size.pass.cpp(33) : warning C6326: Potential comparison of a constant with another constant.
d:\contest\gl0qojfu.5pe\src\qa\vc\libs\libcxx\upstream\test\std\containers\sequences\vector.bool\size.pass.cpp(52) : warning C6326: Potential comparison of a constant with another constant.

The corresponding test for vector::size asserts assert(c.size() == 3);, so I changed it to do that here.

llvm-svn: 318812