Disable rapidcheck tests in the coverage run

https://hydra.nixos.org/build/233688539

src/libexpr/tests/derived-path.cc

@@ -18,6 +18,8 @@ TEST_F(DerivedPathExpressionTest, force_init)
 {
 }
 
+#ifndef COVERAGE
+
 RC_GTEST_FIXTURE_PROP(
     DerivedPathExpressionTest,
     prop_opaque_path_round_trip,
@@ -61,4 +63,6 @@ RC_GTEST_FIXTURE_PROP(
     RC_ASSERT(SingleDerivedPath { b } == d);
 }
 
+#endif
+
 } /* namespace nix */

src/libexpr/tests/value/context.cc

@@ -147,6 +147,8 @@ Gen<NixStringContextElem> Arbitrary<NixStringContextElem>::arbitrary()
 
 namespace nix {
 
+#ifndef COVERAGE
+
 RC_GTEST_PROP(
     NixStringContextElemTest,
     prop_round_rip,
@@ -155,4 +157,6 @@ RC_GTEST_PROP(
     RC_ASSERT(o == NixStringContextElem::parse(o.to_string()));
 }
 
+#endif
+
 }