msvs: Support producing both vcproj and vcxproj depending on configure variables

Change-Id: Ifa27c7064118c24401ea4e55a64e129c4f503cd5

solution.mk

diff --git a/solution.mk b/solution.mk
index 948305f..2c8d29a 100644
--- a/solution.mk
+++ b/solution.mk
@@ -9,14 +9,14 @@
 ##
 
 # libvpx reverse dependencies (targets that depend on libvpx)
-VPX_NONDEPS=$(addsuffix .vcproj,vpx gtest obj_int_extract)
+VPX_NONDEPS=$(addsuffix .$(VCPROJ_SFX),vpx gtest obj_int_extract)
 VPX_RDEPS=$(foreach vcp,\
-              $(filter-out $(VPX_NONDEPS),$^), --dep=$(vcp:.vcproj=):vpx)
+              $(filter-out $(VPX_NONDEPS),$^), --dep=$(vcp:.$(VCPROJ_SFX)=):vpx)
 
-vpx.sln: $(wildcard *.vcproj)
+vpx.sln: $(wildcard *.$(VCPROJ_SFX))
 	@echo "    [CREATE] $@"
 	$(SRC_PATH_BARE)/build/make/gen_msvs_sln.sh \
-            $(if $(filter vpx.vcproj,$^),$(VPX_RDEPS)) \
+            $(if $(filter vpx.$(VCPROJ_SFX),$^),$(VPX_RDEPS)) \
             --dep=vpx:obj_int_extract \
             --dep=test_libvpx:gtest \
             --ver=$(CONFIG_VS_VERSION)\