Address macOS (arm) and FreeBSD buildbot issues

Author: Erlend E. Aasland

configure

@@ -11021,10 +11021,10 @@ $as_echo "yes" >&6; }
 fi
 as_fn_append LIBSQLITE3_CFLAGS ' -I$(srcdir)/Modules/_sqlite'
 
-save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
 save_LDFLAGS=$LDFLAGS
-CFLAGS=$LIBSQLITE3_CFLAGS
-LDFLAGS=$LIBSQLITE3_LIBS
+CPPFLAGS="$LIBSQLITE3_CFLAGS $CFLAGS"
+LDFLAGS="$LIBSQLITE3_LIBS $LDFLAGS"
 
 ac_fn_c_check_header_mongrel "$LINENO" "sqlite3.h" "ac_cv_header_sqlite3_h" "$ac_includes_default"
 if test "x$ac_cv_header_sqlite3_h" = xyes; then :
@@ -11147,7 +11147,7 @@ fi
 
 
 
-CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
 LDFLAGS=$save_LDFLAGS
 
 # Check for support for loadable sqlite extensions

configure.ac

@@ -3174,10 +3174,12 @@ PKG_CHECK_MODULES(
 )
 AS_VAR_APPEND([LIBSQLITE3_CFLAGS], [' -I$(srcdir)/Modules/_sqlite'])
 
-AS_VAR_COPY([save_CFLAGS], [CFLAGS])
+dnl bpo-45774/GH-29507: The CPP check in AC_CHECK_HEADER can fail on FreeBSD,
+dnl hence CPPFLAGS instead of CFLAGS.
+AS_VAR_COPY([save_CPPFLAGS], [CPPFLAGS])
 AS_VAR_COPY([save_LDFLAGS], [LDFLAGS])
-AS_VAR_COPY([CFLAGS], [LIBSQLITE3_CFLAGS])
-AS_VAR_COPY([LDFLAGS], [LIBSQLITE3_LIBS])
+CPPFLAGS="$LIBSQLITE3_CFLAGS $CFLAGS"
+LDFLAGS="$LIBSQLITE3_LIBS $LDFLAGS"
 
 AC_CHECK_HEADER([sqlite3.h], [
   AC_CHECK_LIB([sqlite3], [sqlite3_open_v2], [
@@ -3194,7 +3196,7 @@ AC_CHECK_HEADER([sqlite3.h], [
   AC_CHECK_LIB([sqlite3], [sqlite3_load_extension])
 ])
 
-AS_VAR_COPY([CFLAGS], [save_CFLAGS])
+AS_VAR_COPY([CPPFLAGS], [save_CPPFLAGS])
 AS_VAR_COPY([LDFLAGS], [save_LDFLAGS])
 
 # Check for support for loadable sqlite extensions