Remove unnecessary inclusions of compiler-static_assert.h

Various files included compiler-static_assert.h to use the compatibility
macros for compilers that lacked a working C++11 static_assert.
However, some source files used static_assert without this inclusion,
and no one ever reported problems.  From this, assume that no one uses a
compiler which lacks C++11 static_assert.  Remove the inclusions that
were only for the compatibility macro.  Keep the inclusions that use the
assert_equal helper.

common/include/physfsx.h

@@ -41,7 +41,6 @@
 #include "ntstring.h"
 #include "compiler-array.h"
 #include "compiler-make_unique.h"
-#include "compiler-static_assert.h"
 #include "partial_range.h"
 
 #ifdef DXX_CONSTANT_TRUE

common/include/valptridx.h

@@ -11,7 +11,6 @@
 #include <type_traits>
 #include "fwd-valptridx.h"
 #include "compiler-array.h"
-#include "compiler-static_assert.h"
 #include "pack.h"
 #include "compiler-poison.h"
 

common/main/player.h

@@ -36,7 +36,6 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "pack.h"
 #include "dxxsconf.h"
 #include "compiler-array.h"
-#include "compiler-static_assert.h"
 #include "objnum.h"
 #include "player-callsign.h"
 

similar/main/collide.cpp

@@ -86,7 +86,6 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "dxxsconf.h"
 #include "dsx-ns.h"
 #include "compiler-integer_sequence.h"
-#include "compiler-static_assert.h"
 
 using std::min;
 

similar/main/net_udp.cpp

@@ -66,7 +66,6 @@
 #include "compiler-exchange.h"
 #include "compiler-range_for.h"
 #include "compiler-lengthof.h"
-#include "compiler-static_assert.h"
 #include "partial_range.h"
 
 #if defined(DXX_BUILD_DESCENT_I)

similar/main/piggy.cpp

@@ -58,7 +58,6 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "console.h"
 #include "compiler-range_for.h"
 #include "compiler-make_unique.h"
-#include "compiler-static_assert.h"
 #include "partial_range.h"
 
 #if defined(DXX_BUILD_DESCENT_I)