Allow to set LO_ELFCHECK_ALLOWLIST in autogen.input

(To minimize disruption with other people's potential use of the variable, when
it is not set during configuration make sure not to export it as empty from
config_host.mk, so that it can then still be passed as an environment variable
to individual `make` invocations.)

Change-Id: I785910f1076c05905e354ef846d16ffb7ea0a081
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/101002
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

config_host.mk.in

@@ -395,6 +395,7 @@ export LIBXML_JAR=@LIBXML_JAR@
 export LIBXML_LIBS=$(gb_SPACE)@LIBXML_LIBS@
 export LIBXSLT_CFLAGS=$(gb_SPACE)@LIBXSLT_CFLAGS@
 export LIBXSLT_LIBS=$(gb_SPACE)@LIBXSLT_LIBS@
+@x_LO_ELFCHECK_ALLOWLIST@ export LO_ELFCHECK_ALLOWLIST=@LO_ELFCHECK_ALLOWLIST@
 @x_Cygwin@ export LS=@WIN_LS@
 export MACOSX_BUNDLE_IDENTIFIER=@MACOSX_BUNDLE_IDENTIFIER@
 export MACOSX_CODESIGNING_IDENTITY=@MACOSX_CODESIGNING_IDENTITY@

configure.ac

@@ -13570,6 +13570,15 @@ fi
 
 AC_SUBST(LO_PATH)
 
+# Allow to pass LO_ELFCHECK_ALLOWLIST from autogen.input to bin/check-elf-dynamic-objects:
+if test "$LO_ELFCHECK_ALLOWLIST" = x || test "${LO_ELFCHECK_ALLOWLIST-x}" != x; then
+    x_LO_ELFCHECK_ALLOWLIST=
+else
+    x_LO_ELFCHECK_ALLOWLIST=[\#]
+fi
+AC_SUBST(x_LO_ELFCHECK_ALLOWLIST)
+AC_SUBST(LO_ELFCHECK_ALLOWLIST)
+
 libo_FUZZ_SUMMARY
 
 # Generate a configuration sha256 we can use for deps