Get value of variable instead of using the variable name itself.

src/openscenegraph.mk

@@ -33,7 +33,7 @@ define $(PKG)_BUILD
         -DPOPPLER_HAS_CAIRO_EXITCODE=0 \
         -D_OPENTHREADS_ATOMIC_USE_GCC_BUILTINS_EXITCODE=1 \
         -D_OPENTHREADS_ATOMIC_USE_WIN32_INTERLOCKED=1 \
-        $(if $(filter qtbase,$(PKG)_DEPS), \
+        $(if $(filter qtbase,$($(PKG)_DEPS)), \
           -DDESIRED_QT_VERSION=4, \
           -DDESIRED_QT_VERSION=5)
     $(MAKE) -C '$(1).build' -j '$(JOBS)' install VERBOSE=1

src/poppler.mk

@@ -27,7 +27,7 @@ define $(PKG)_BUILD
         $(MXE_CONFIGURE_OPTS) \
         --disable-silent-rules \
         --enable-xpdf-headers \
-        $(if $(filter qtbase,$(PKG)_DEPS), \
+        $(if $(filter qtbase,$($(PKG)_DEPS)), \
           --enable-poppler-qt4 \
           --disable-poppler-qt5, \
           --disable-poppler-qt4 \