Prevent VERSION from being picked up as C++20 <version> standard …

…header.

- Move `config.h` (created by `configure`) from main directory to `unix` subdirectory
- Fix some instances in `prebuild.sh` where we're adding the main directory to the include search path for no obvious reason.

This should fix GitHub issue #403 for v3.8.

.gitignore

@@ -177,7 +177,6 @@ $RECYCLE.BIN/
 /VERSION
 /aclocal.m4
 /bootstrap
-/config.h.in
 /configure
 /configure.ac
 /kde_install.sh
@@ -191,6 +190,7 @@ $RECYCLE.BIN/
 /source/Makefile.in
 /unix/Makefile.am
 /unix/Makefile.in
+/unix/config.h.in
 /unix/config/ar-lib
 /unix/config/compile
 /unix/config/config.guess
@@ -209,13 +209,13 @@ $RECYCLE.BIN/
 
 # Files created by configure script in main directory
 /Makefile
-/config.h
 /config.status
-/stamp-h1
 # Files created by configure script in specific subdirectories
 /platform/Makefile
 /source/Makefile
 /unix/Makefile
+/unix/config.h
+/unix/stamp-h1
 /vfe/Makefile
 # Directories created by configure script
 .deps/

changes.txt

@@ -120,6 +120,7 @@ Reported via GitHub:
     -lboost_system with Boost 1.66)
   - #342 ("AX_FIX_INCORRECT_PATH is broken", configure script failing to
     properly handle `.` directory in `C_INCLUDE_PATH` or `CPLUS_INCLUDE_PATH`)
+  - #403 ("povray 3.7.0.8 does not build on macOS 11.0 Big Sur").
 
 Reported via the Newsgroups:
 

unix/configure.ac

@@ -50,7 +50,7 @@ VERSION_BASE=`echo $PACKAGE_VERSION | sed 's,\([[0-9]]*.[[0-9]]*\).*,\1,g'`
 AC_SUBST([VERSION_BASE])
 AC_DEFINE_UNQUOTED([VERSION_BASE], ["$VERSION_BASE"], [Base version number of package.])
 AC_CONFIG_AUX_DIR([unix/config])
-AC_CONFIG_HEADERS([config.h])
+AC_CONFIG_HEADERS([unix/config.h])
 AC_CONFIG_SRCDIR([unix/disp_text.cpp])
 
 # Additional autoconf macros.

unix/prebuild.sh

@@ -453,7 +453,6 @@ endif
 # Include paths for headers.
 AM_CPPFLAGS = \\
   -I\$(top_srcdir)/unix/povconfig \\
-  -I\$(top_srcdir) \\
   -I\$(top_srcdir)/source \\
   -I\$(top_builddir)/source \\
   -I\$(top_srcdir)/platform/unix \\
@@ -825,7 +824,6 @@ endif
 # Include paths for headers.
 AM_CPPFLAGS = \\
   -I\$(top_srcdir)/unix/povconfig \\
-  -I\$(top_srcdir) \\
   -I\$(top_srcdir)/platform/unix \\
   \$(cppflags_platformcpu) \\
   -I\$(top_srcdir)/unix \\