Fix symbol visibility (#26)

This was broken as binutils wasn't being installed in the frontend in non-cross builds.
* Check if frontend for tuple compare in binutils build
* Add test for symbol visibility
* funcs: Use TARGET_PREFIX

makes/src/30-binutils.sh

@@ -44,7 +44,7 @@ process_background "Building binutils" \
 process_background "Installing binutils" \
     make DESTDIR="${BUILD_DIR}/binutils-install" \
     install-strip || die "binutils install failed"
-if is_step_backend; then
+if is_step_backend || (is_step_frontend && [ "$WPI_BUILD_TUPLE" == "$WPI_HOST_TUPLE" ]); then
     # GCC needs binutils in prefix path while building
     # the target libraries. Previously this required
     # the build user to have root access, but now

makes/src/utils/funcs.sh

@@ -61,11 +61,11 @@ configure_host_vars() {
 }
 
 configure_target_vars() {
-    env_exists TARGET_TUPLE
+    env_exists TARGET_PREFIX
 
     define_target_export() {
         local var="${1}_FOR_TARGET"
-        local tool="${TARGET_TUPLE}-$2"
+        local tool="${TARGET_PREFIX}$2"
         if [ "${!var}" ]; then
             die "$var is already set with '${!var}'"
         else

utils/test-toolchain.sh

@@ -76,6 +76,8 @@ echo "[INFO]: Testing C Compiler with libasan"
 "$CC" "${TEST_DIR}/hello.c" -o /dev/null -fsanitize=address || exit
 echo "[INFO]: Testing C Compiler with libubsan"
 "$CC" "${TEST_DIR}/hello.c" -o /dev/null -fsanitize=undefined || exit
+echo "[INFO]: Testing C Compiler with symbol visibility"
+"$CC" "${TEST_DIR}/hello.c" -o /dev/null -fvisibility=hidden -Werror || exit
 
 if [ "${TARGET_ENABLE_CXX}" = "true" ]; then
     echo "[INFO]: Testing C++ Compiler"
@@ -84,6 +86,8 @@ if [ "${TARGET_ENABLE_CXX}" = "true" ]; then
     "$CXX" "${TEST_DIR}/hello.cpp" -o /dev/null -fsanitize=address || exit
     echo "[INFO]: Testing C++ Compiler with libubsan"
     "$CXX" "${TEST_DIR}/hello.cpp" -o /dev/null -fsanitize=undefined || exit
+    echo "[INFO]: Testing C++ Compiler with symbol visibility"
+    "$CXX" "${TEST_DIR}/hello.cpp" -o /dev/null -fvisibility=hidden -Werror || exit
 fi
 
 if [ "${TARGET_ENABLE_FORTRAN}" = "true" ]; then