Remove several unnecessary test patches
    
    - gdb-physname-pr11734-test.patch
    - gdb-physname-pr12273-test.patch
    These two tests were merged upstream under a different file name.
    
    - gdb-runtest-pie-override.patch
    This patch appears unnecessary today. I have tested on all supported
    host architectures and detected no regressions. I presume this was
    fixed in a different manner through the years.
    
    - gdb-test-expr-cumulative-archer.patch
    The patch contains two tests. Both are upstream already.
    While one is a little more involved than what landed upstream,
    both tests are equivalent. The other test, gdb.cp/namespace-no-imports.exp,
    is identical to upstream's gdb.cp/nsnoimports.exp with whitespace
    and other trivial changes.