Remove CATCH_CONFIG_DISABLE_MATCHERS

Now that the recommended distribution and usage method is proper
library, users can just avoid including the matcher headers to get
basically the same effect.

tests/SelfTest/UsageTests/Exception.tests.cpp

@@ -162,8 +162,6 @@ TEST_CASE("thrown std::strings are translated", "[.][failing][!throws]") {
 }
 
 
-#ifndef CATCH_CONFIG_DISABLE_MATCHERS
-
 TEST_CASE( "Exception messages can be tested for", "[!throws]" ) {
     using namespace Catch::Matchers;
     SECTION( "exact match" )
@@ -178,8 +176,6 @@ TEST_CASE( "Exception messages can be tested for", "[!throws]" ) {
     }
 }
 
-#endif
-
 TEST_CASE( "Mismatching exception messages failing the test", "[.][failing][!throws]" ) {
     REQUIRE_THROWS_WITH( thisThrows(), "expected exception" );
     REQUIRE_THROWS_WITH( thisThrows(), "should fail" );