libepoxy: fix EPOXY_IMPORTEXPORT for static target

See https://github.com/mxe/mxe/issues/1647#issuecomment-275967915

src/libepoxy-1-fixes.patch

@@ -0,0 +1,34 @@
+This file is part of MXE. See LICENSE.md for licensing information.
+
+Contains ad hoc patches for cross building.
+
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Boris Nagaev <bnagaev@gmail.com>
+Date: Tue, 31 Jan 2017 02:03:55 +0100
+Subject: [PATCH] fix EPOXY_IMPORTEXPORT for static targets
+
+Based on https://github.com/mxe/mxe/issues/1647#issuecomment-275967915
+
+diff --git a/include/epoxy/gl.h b/include/epoxy/gl.h
+index 1111111..2222222 100644
+--- a/include/epoxy/gl.h
++++ b/include/epoxy/gl.h
+@@ -71,7 +71,17 @@ extern "C" {
+ #endif
+ 
+ #ifndef EPOXY_IMPORTEXPORT
+-#define EPOXY_IMPORTEXPORT __declspec(dllimport)
++#  ifdef EPOXY_SHARED
++#    ifdef EPOXY_DLL
++#      define EPOXY_IMPORTEXPORT __declspec(dllexport)
++#    else
++#      define EPOXY_IMPORTEXPORT __declspec(dllimport)
++#    endif
++#  elif EPOXY_STATIC
++#    define EPOXY_IMPORTEXPORT
++#  else
++#    error "Please define EPOXY_STATIC or EPOXY_SHARED"
++#  endif
+ #endif
+ 
+ #ifndef GLAPI

src/libepoxy.mk

@@ -19,7 +19,11 @@ endef
 
 define $(PKG)_BUILD
     cd '$(1)' && autoreconf -fi -I'$(PREFIX)/$(TARGET)/share/aclocal'
-    cd '$(1)' && ./configure \
+    cd '$(1)' && \
+        CFLAGS='$(if $(BUILD_STATIC),-DEPOXY_STATIC,-DEPOXY_SHARED -DEPOXY_DLL)' \
+        ./configure \
         $(MXE_CONFIGURE_OPTS)
     $(MAKE) -C '$(1)' -j '$(JOBS)' install $(MXE_DISABLE_CRUFT)
+    $(SED) 's/Cflags:/Cflags: -DEPOXY_$(if $(BUILD_STATIC),STATIC,SHARED)/' \
+        -i '$(PREFIX)/$(TARGET)/lib/pkgconfig/epoxy.pc'
 endef