Fix error handling for dynamic loading. (#102)

* Fix error handling for dynamic loading.

* Install newer version of cmake.

* Fix cmake installation.

Author: rnburn

ci/setup_linux_environment.sh

@@ -8,3 +8,8 @@ sudo apt-get update -o Dir::Etc::sourcelist="sources.list.d/bazel.list" \
     -o Dir::Etc::sourceparts="-" \
     -o APT::Get::List-Cleanup="0"
 sudo apt-get install openjdk-8-jdk bazel
+sudo apt-get install software-properties-common
+
+sudo add-apt-repository ppa:george-edison55/cmake-3.x -y
+sudo apt-get update
+sudo apt-get install cmake

src/dynamic_load_unix.cpp

@@ -74,7 +74,7 @@ DynamicallyLoadTracingLibrary(const char* shared_library,
     if (error_message.empty()) {
       error_message = error_code.message();
     }
-    return make_unexpected(error_code);
+    return make_unexpected(dynamic_load_failure_error);
   }
 
   if (tracer_factory == nullptr) {