[lldb] [testsuite] TestGdbRemoteLibrariesSvr4Support: Fix symlinked builddir

[lldb] [testsuite] TestGdbRemoteLibrariesSvr4Support: Fix symlinked builddir

When I have symlinked builddir on Fedora 31 x86_64 I get:

	FAIL: test_libraries_svr4_libs_present (TestGdbRemoteLibrariesSvr4Support.TestGdbRemoteLibrariesSvr4Support)
	----------------------------------------------------------------------
	...
	  File "lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/TestGdbRemoteLibrariesSvr4Support.py", line 106, in
	libraries_svr4_libs_present
	    self.assertIn(self.getBuildDir() + "/" + lib, libraries_svr4_names)
	AssertionError:
	'/home/jkratoch/redhat/llvm-monorepo-clangassertsymlink/lldb-test-build.noindex/tools/lldb-server/libraries-svr4/TestGdbRemoteLibrariesSvr4Support.test_libraries_svr4_libs_present/libsvr4lib_a.so' not found in ['/home/jkratoch/redhat/llvm-monorepo/lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/linux-vdso.so.1', '/quad/home/jkratoch/redhat/llvm-monorepo-clangassertsymlink/lldb-test-build.noindex/tools/lldb-server/libraries-svr4/TestGdbRemoteLibrariesSvr4Support.test_libraries_svr4_libs_present/libsvr4lib_a.so', '/quad/home/jkratoch/redhat/llvm-monorepo-clangassertsymlink/lldb-test-build.noindex/tools/lldb-server/libraries-svr4/TestGdbRemoteLibrariesSvr4Support.test_libraries_svr4_libs_present/libsvr4lib_b".so', '/usr/lib64/libdl-2.30.so', '/usr/lib64/libstdc++.so.6.0.27', '/usr/lib64/libm-2.30.so', '/usr/lib64/libgcc_s-9-20190827.so.1', '/usr/lib64/libc-2.30.so', '/usr/lib64/ld-2.30.so']
	Config=x86_64-/quad/home/jkratoch/redhat/llvm-monorepo-clangassertsymlink/bin/clang-11
	----------------------------------------------------------------------

Differential Revision: https://reviews.llvm.org/D74295