Fix linking to imported libraries test.

Make a C executable instead of attempting to make a C++ static
library (and not really succeeding). This was introduced in
commit 894f52f3 (Handle INTERFACE properties transitively for
includes and defines., 2012-09-23).

Tests/ExportImport/Import/A/CMakeLists.txt

@@ -157,8 +157,8 @@ endif()
 # Test that dependent imported targets have usable
 # INTERFACE_COMPILE_DEFINITIONS and INTERFACE_INCLUDE_DIRECTORIES
 
-add_library(deps_iface deps_iface.cpp)
-target_link_libraries(deps_iface testLibsDepends)
+add_executable(deps_iface deps_iface.c)
+target_link_libraries(deps_iface testLibDepends)
 set_property(TARGET deps_iface APPEND PROPERTY
   COMPILE_DEFINITIONS
     $<TARGET_PROPERTY:testLibDepends,INTERFACE_COMPILE_DEFINITIONS>

Tests/ExportImport/Import/A/deps_iface.cpp → Tests/ExportImport/Import/A/deps_iface.c

@@ -18,7 +18,7 @@
 extern int testLibDepends(void);
 
 
-int main(int,char **)
+int main()
 {
   return testLibDepends();
 }