support building without dlopen support

Conflicts:
	SConstruct

SConstruct

@@ -443,6 +443,7 @@ pickle_store = [# Scons internal variables
         'PYTHON_SYS_PREFIX',
         'COLOR_PRINT',
         'HAS_CAIRO',
+        'MAPNIK_HAS_DLFCN',
         'HAS_PYCAIRO',
         'HAS_LIBXML2',
         'PYTHON_IS_64BIT',
@@ -829,6 +830,24 @@ int main()
         rm_path(item,'CPPPATH',context.env)
     return ret
 
+def CheckHasDlfcn(context, silent=False):
+    if not silent:
+        context.Message('Checking for dlfcn.h support ... ')
+    ret = context.TryCompile("""
+
+#include <dlfcn.h>
+
+int main()
+{
+    return 0;
+}
+
+""", '.cpp')
+    if silent:
+        context.did_show_result=1
+    context.Result(ret)
+    return ret
+
 def GetBoostLibVersion(context):
     ret = context.TryRun("""
 
@@ -989,6 +1008,7 @@ conf_tests = { 'prioritize_paths'      : prioritize_paths,
                'FindBoost'             : FindBoost,
                'CheckBoost'            : CheckBoost,
                'CheckCairoHasFreetype' : CheckCairoHasFreetype,
+               'CheckHasDlfcn'         : CheckHasDlfcn,
                'GetBoostLibVersion'    : GetBoostLibVersion,
                'parse_config'          : parse_config,
                'parse_pg_config'       : parse_pg_config,
@@ -1199,6 +1219,11 @@ if not preconfigured:
         ['harfbuzz', 'harfbuzz/hb.h',True,'C++']
     ]
 
+    if conf.CheckHasDlfcn():
+        env.Append(CPPDEFINES = '-DMAPNIK_HAS_DLCFN')
+    else:
+        env['SKIPPED_DEPS'].extend(['dlfcn'])
+
     OPTIONAL_LIBSHEADERS = []
 
     if env['JPEG']:

src/plugin.cpp

@@ -31,7 +31,9 @@
   #define dlclose FreeLibrary
   #define dlerror GetLastError
 #else
+  #ifdef MAPNIK_HAS_DLCFN
     #include <dlfcn.h>
+  #endif
   #define handle void *
 #endif
 
@@ -52,29 +54,44 @@ PluginInfo::PluginInfo(std::string const& filename,
       {
 #ifdef _WINDOWS
           if (module_) module_->dl = LoadLibraryA(filename.c_str());
+          if (module_ && module_->dl)
+          {
+                name_func* name = reinterpret_cast<name_func*>(dlsym(module_->dl, library_name.c_str()));
+                if (name) name_ = name();
+          }
 #else
+  #ifdef MAPNIK_HAS_DLCFN
           if (module_) module_->dl = dlopen(filename.c_str(),RTLD_LAZY);
-#endif
           if (module_ && module_->dl)
           {
                 name_func name = reinterpret_cast<name_func>(dlsym(module_->dl, library_name.c_str()));
                 if (name) name_ = name();
           }
+  #else
+          throw std::runtime_error("no support for loading dynamic objects (Mapnik not compiled with -DMAPNIK_HAS_DLCFN)");
+  #endif
+#endif
       }
 
 PluginInfo::~PluginInfo()
 {
     if (module_)
     {
+#ifdef MAPNIK_HAS_DLCFN
         if (module_->dl) dlclose(module_->dl),module_->dl=0;
         delete module_;
+#endif
     }
 }
 
 
 void * PluginInfo::get_symbol(std::string const& sym_name) const
 {
+#ifdef MAPNIK_HAS_DLCFN
     return static_cast<void *>(dlsym(module_->dl, sym_name.c_str()));
+#else
+    return NULL;
+#endif
 }
 
 std::string const& PluginInfo::name() const