Remove a couple of redundant lines from the makefile

Fixes the last case of 17744.

changes/bug17744_redux

@@ -0,0 +1,5 @@
+  o Minor bugfixes (build):
+    - Remove a pair of redundant AM_CONDITIONAL declarations from
+      configure.ac. Fixes one final case of bug 17744; bugfix on
+      0.2.8.2-alpha.
+

configure.ac

@@ -58,8 +58,6 @@ fi
 
 AM_CONDITIONAL(UNITTESTS_ENABLED, test "x$enable_unittests" != "xno")
 AM_CONDITIONAL(COVERAGE_ENABLED, test "x$enable_coverage" = "xyes")
-AM_CONDITIONAL(UNITTESTS_ENABLED, test x$enable_unittests != xno)
-AM_CONDITIONAL(COVERAGE_ENABLED, test x$enable_coverage = xyes)
 AM_CONDITIONAL(DISABLE_ASSERTS_IN_UNIT_TESTS, test "x$enable_asserts_in_tests" = "xno")
 
 if test "$enable_static_tor" = "yes"; then