freeglut: gcc 10 compatibility fix

src/freeglut-1-fixes.patch

@@ -5,7 +5,7 @@ Contains ad hoc patches for cross building.
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Boris Pek <tehnick-8@yandex.ru>
 Date: Sat, 18 Jun 2016 16:24:52 +0300
-Subject: [PATCH 1/2] Back compatibility with older freeglut packages in MXE
+Subject: [PATCH 1/3] Back compatibility with older freeglut packages in MXE
 
 
 diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -75,7 +75,7 @@ index 1111111..2222222 100644
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Boris Nagaev <bnagaev@gmail.com>
 Date: Thu, 14 Jul 2016 19:15:17 +0300
-Subject: [PATCH 2/2] add glu to requirements in .pc file
+Subject: [PATCH 2/3] add glu to requirements in .pc file
 
 glu.pc is generated by mxe-conf and it adds -lglu32 to linker flags.
 libglu32.a defines gluUnProject and other symbols used by users of GLU.
@@ -93,3 +93,57 @@ index 1111111..2222222 100644
  Libs.private: @PC_LIBS_PRIVATE@
  Cflags: -I${includedir} @PC_CFLAGS@
 +Requires: glu
+
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Mark Brand <mabrand@mabrand.nl>
+Date: Thu, 28 May 2020 12:36:54 +0200
+Subject: [PATCH 3/3] gcc 10 compatibility: add missing "extern"
+
+Related to:
+        Default to -fno-common
+        https://gcc.gnu.org/gcc-10/porting_to.html
+
+diff --git a/src/fg_gl2.c b/src/fg_gl2.c
+index 1111111..2222222 100644
+--- a/src/fg_gl2.c
++++ b/src/fg_gl2.c
+@@ -27,6 +27,14 @@
+ #include "fg_internal.h"
+ #include "fg_gl2.h"
+ 
++FGH_PFNGLGENBUFFERSPROC fghGenBuffers;
++FGH_PFNGLDELETEBUFFERSPROC fghDeleteBuffers;
++FGH_PFNGLBINDBUFFERPROC fghBindBuffer;
++FGH_PFNGLBUFFERDATAPROC fghBufferData;
++FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC fghEnableVertexAttribArray;
++FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC fghDisableVertexAttribArray;
++FGH_PFNGLVERTEXATTRIBPOINTERPROC fghVertexAttribPointer;
++
+ void FGAPIENTRY glutSetVertexAttribCoord3(GLint attrib) {
+   if (fgStructure.CurrentWindow != NULL)
+     fgStructure.CurrentWindow->Window.attribute_v_coord = attrib;
+diff --git a/src/fg_gl2.h b/src/fg_gl2.h
+index 1111111..2222222 100644
+--- a/src/fg_gl2.h
++++ b/src/fg_gl2.h
+@@ -67,13 +67,13 @@ typedef void (APIENTRY *FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC) (GLuint index);
+ typedef void (APIENTRY *FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC) (GLuint);
+ typedef void (APIENTRY *FGH_PFNGLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
+ 
+-FGH_PFNGLGENBUFFERSPROC fghGenBuffers;
+-FGH_PFNGLDELETEBUFFERSPROC fghDeleteBuffers;
+-FGH_PFNGLBINDBUFFERPROC fghBindBuffer;
+-FGH_PFNGLBUFFERDATAPROC fghBufferData;
+-FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC fghEnableVertexAttribArray;
+-FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC fghDisableVertexAttribArray;
+-FGH_PFNGLVERTEXATTRIBPOINTERPROC fghVertexAttribPointer;
++extern FGH_PFNGLGENBUFFERSPROC fghGenBuffers;
++extern FGH_PFNGLDELETEBUFFERSPROC fghDeleteBuffers;
++extern FGH_PFNGLBINDBUFFERPROC fghBindBuffer;
++extern FGH_PFNGLBUFFERDATAPROC fghBufferData;
++extern FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC fghEnableVertexAttribArray;
++extern FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC fghDisableVertexAttribArray;
++extern FGH_PFNGLVERTEXATTRIBPOINTERPROC fghVertexAttribPointer;
+ 
+ #    endif
+