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

…header.

- Move `config.h` (created by `configure`) from main directory to `unix` subdirectory
- Move original `VERSION` from `unix` to `unix/prebuild` 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.

changes.txt

@@ -46,6 +46,11 @@ Fixed or Mitigated Bugs
     "Building on postmarketOS on PinePhone").
   - Eliminate uint type from platform-independent code (concludes fix of
     GitHub issue #400, "Building on postmarketOS on PinePhone").
+  - Change locations of auto-generated `config.h` and origonal `VERSION` file
+    to prevent the latter or its copy from erroneously being picked up on some
+    systems as `<version>` standard C++20 include file by libraries (notably
+    boost thread 1.73 and later; fixes GitHub issue #403, "povray 3.7.0.8 does
+    not build on macOS 11.0 Big Sur").
 
 
 Changes between 3.7.0.7 and 3.7.0.8

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

@@ -44,7 +44,7 @@
 
 umask 022
 
-pov_version_base=`cat ./VERSION | sed 's,\([0-9]*.[0-9]*\).*,\1,g'`
+pov_version_base=`cat ./prebuild/VERSION | sed 's,\([0-9]*.[0-9]*\).*,\1,g'`
 pov_config_bugreport="POV-Ray Bugtracker http://bugs.povray.org/"
 
 # documentation
@@ -350,7 +350,7 @@ echo "make maintainer-clean" 1>&2  &&  make maintainer-clean 1>&2 ; \
   # some shells seem unable to expand properly wildcards in the list entries
   # (e.g. ../distribution/in*/).
   for file in \
-    AUTHORS ChangeLog configure.ac COPYING NEWS README VERSION \
+    AUTHORS ChangeLog configure.ac COPYING NEWS README prebuild/VERSION \
     povray.1 povray.conf \
     scripts \
     ../distribution/ini ../distribution/include ../distribution/scenes
@@ -425,7 +425,6 @@ povray_SOURCES = \\
 
 # Include paths for headers.
 AM_CPPFLAGS = \\
-  -I\$(top_srcdir) \\
   -I\$(top_srcdir)/source \\
   -I\$(top_builddir)/source \\
   -I\$(top_srcdir)/source/backend \\
@@ -789,7 +788,6 @@ libpovray_a_SOURCES = \\
 
 # Include paths for headers.
 AM_CPPFLAGS = \\
-  -I\$(top_srcdir) \\
   -I\$(top_srcdir)/source/backend \\
   -I\$(top_srcdir)/source/base \\
   -I\$(top_srcdir)/source/frontend \\