tests: Build test cases with their respective c++ files

Tested:
    Unit tests still build and pass as expected.

Change-Id: I20b117dcc07c5338ca300303c52df04f3a0e3ff1
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 4370a4d..62fc099 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -22,7 +22,7 @@
 handle_CPPFLAGS = $(gtest_cppflags)
 handle_LDADD = $(gtest_ldadd)
 
-check_PROGRAMS += internal_fd
+check_PROGRAMS += internal/fd
 internal_fd_SOURCES = internal/fd.cpp
 internal_fd_CPPFLAGS = $(gtest_cppflags)
 internal_fd_LDADD = $(gtest_ldadd)