fails to build with GLEW 1.12.0

[pabs]

warzone2100 fails to build with GLEW 1.12.0, it seems like the GLEW API has changed:

g++ -DHAVE_CONFIG_H -I. -I../..  -I/usr/include/libpng12    -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -DNDEBUG -DWZ_DATADIR="\"/usr/share/games/warzone2100\"" -DLOCALEDIR="\"/usr/share/locale\"" -I../.. -I/usr/include/libdrm  -DQT_SHARED -I/usr/include/qt4 -I/usr/include/qt4/QtNetwork -I/usr/include/qt4 -I/usr/include/qt4/QtScript -I/usr/include/qt4 -I/usr/include/qt4/QtCore  -D_FORTIFY_SOURCE=2 -g -Wno-enum-compare -Wall -Wextra -Wno-unused-parameter -Wno-sign-compare -Wcast-align -Wwrite-strings -Wpointer-arith -Wno-format-security -DQT_SHARED -I/usr/include/qt4 -I/usr/include/qt4/QtNetwork -I/usr/include/qt4 -I/usr/include/qt4/QtScript -I/usr/include/qt4 -I/usr/include/qt4/QtCore  -g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -fstack-protector -c -o screen.o screen.cpp
screen.cpp: In function 'void screen_EnableMissingFunctions()':
screen.cpp:264:22: error: invalid conversion from 'PFNGLSHADERSOURCEARBPROC {aka void (*)(unsigned int, int, const char**, const int*)}' to 'PFNGLSHADERSOURCEPROC {aka void (*)(unsigned int, int, const char* const*, const int*)}' [-fpermissive]
   __glewShaderSource = __glewShaderSourceARB;
                      ^
Makefile:423: recipe for target 'screen.o' failed

[Per]

This bug appears inside a hideous hack to support pre-OpenGL 2.0 systems, which presumes too much about GLEW internals. I would not mind ripping it out. Or if Debian ripped it out before distributing - just remove the whole function and one place where it is called.

[Per]

This code is all gone in master, BTW.

[Per Inge Mathisen <per.mathisen@…>]

In d512d1dc9857e3c2bbfa0a7b5856bdf420412b8f:

3.1: Remove hack to support some pre-OpenGL-2.0 systems that made
assumptions about internals in GLEW that breaks with GLEW 1.12.

See ticket:4300 reported by pabs

[vexed]

Actually, this was already reported.
duplicate of #4218

[vexed]

In 6a6c611ca3d9d6745e5343f2ee041892772ccae6:

Resync/backport the code base:

3.1: Remove hack to support some pre-OpenGL-2.0 systems that made
assumptions about internals in GLEW that breaks with GLEW 1.12.

See ticket:4300 reported by pabs

(cherry picked from commit d512d1dc9857e3c2bbfa0a7b5856bdf420412b8f)

Conflicts:
	lib/ivis_opengl/screen.cpp