g3dvl/xlib: fix build by changing include order

g3dvl/xlib: fix build by changing include order

fixes the following build error since
c83fb4d45f2a47042f395271efe6e5489b2c4aee:

/usr/include/strings.h:46:13: error: expected declaration specifiers or
‘...’ before numeric constant
/usr/include/strings.h:46:13: error: conflicting types for ‘memset’
In file included from
../../../../src/gallium/winsys/g3dvl/xlib/xsp_winsys.c:34:0:
../../../../src/gallium/auxiliary/util/u_inlines.h: In function
‘pipe_buffer_create’:
../../../../src/gallium/auxiliary/util/u_inlines.h:189:4: error: too
many arguments to function ‘memset’
/usr/include/strings.h:46:13: note: declared here

bzero is defined in X11 as: #define bzero(b,len) memset(b,0,len)
including strings.h after the X11 header results in preprocessor
replacing 'bzero' in strings.h and generating unbuildable code.

Signed-off-by: Tobias Droste <tdroste@gmx.de>