Actually fix the build

Looks like I was too quick on previous commit.

It seems -pthread is actually not that much needed on Linux though...
although the manpage says "compile and link with -pthread". Go figure.

Now dlopen() uses RTLD_LAZY | RTLD_LOCAL for Linux, which seems
to work here.

src/build/libpackage/Jamfile

@@ -9,6 +9,7 @@ SEARCH_SOURCE += [ FDirName $(HAIKU_TOP) src kits package manager ] ;
 SEARCH_SOURCE += [ FDirName $(HAIKU_TOP) src kits package solver ] ;
 
 USES_BE_API on libpackage_build.so = true ;
+LINKFLAGS on libpackage_build.so += $(HOST_PTHREAD_LINKFLAGS) ;
 
 
 {

src/build/libpackage/solver/Jamfile

@@ -15,8 +15,6 @@ SEARCH_SOURCE += [ FDirName $(HAIKU_TOP) src kits package solver ] ;
 MakeLocate libpackage-add-on-libsolv_build.so
 	: $(HOST_BUILD_COMPATIBILITY_LIB_DIR) ;
 
-LINKFLAGS on libpackage-add-on-libsolv_build.so += $(HOST_PTHREAD_LINKFLAGS) ;
-
 BuildPlatformSharedLibrary libpackage-add-on-libsolv_build.so
 	:
 	LibsolvSolver.cpp

src/kits/package/solver/Solver.cpp

@@ -25,10 +25,14 @@ static pthread_once_t sLoadLibsolvSolverAddOnInitOnce = PTHREAD_ONCE_INIT;
 static void
 load_libsolv_solver_add_on()
 {
+	int flags = 0;
 #ifdef HAIKU_TARGET_PLATFORM_HAIKU
-	void* imageHandle = dlopen("libpackage-add-on-libsolv.so", 0);
+	void* imageHandle = dlopen("libpackage-add-on-libsolv.so", flags);
 #else
-	void* imageHandle = dlopen("libpackage-add-on-libsolv_build.so", 0);
+#ifdef HAIKU_HOST_PLATFORM_LINUX
+	flags = RTLD_LAZY | RTLD_LOCAL;
+#endif
+	void* imageHandle = dlopen("libpackage-add-on-libsolv_build.so", flags);
 #endif
 	if (imageHandle == NULL)
 		return;