Fix for cross compiling

Fixed:
| ./dftables src/pcre2_chartables.c
| make: ./dftables: Command not found
| make: *** [src/pcre2_chartables.c] Error 127

Upstream-Status: Pending

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>

diff --git a/Makefile.am b/Makefile.am
index 38f1d41..2bde083 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -298,9 +298,21 @@ bin_SCRIPTS = pcre2-config
 ## to copy a distributed set of tables that are defined for ASCII code. In this
 ## case, dftables is not needed.
 
+CC_FOR_BUILD = @CC_FOR_BUILD@
+CFLAGS_FOR_BUILD = @CFLAGS_FOR_BUILD@
+CCLD_FOR_BUILD = @CCLD_FOR_BUILD@
+LDFLAGS_FOR_BUILD = @LDFLAGS_FOR_BUILD@
+
 if WITH_REBUILD_CHARTABLES
 noinst_PROGRAMS += dftables
 dftables_SOURCES = src/dftables.c
+
+dftables_LINK = $(CCLD_FOR_BUILD) -o $@
+dftables_LDFLAGS = $(LDFLAGS_FOR_BUILD)
+
+src/dftables.o: $(srcdir)/src/dftables.c
+	$(CC_FOR_BUILD) -c $(CFLAGS_FOR_BUILD) -o $@ $(srcdir)/src/dftables.c
+
 src/pcre2_chartables.c: dftables$(EXEEXT)
 	rm -f $@
 	./dftables$(EXEEXT) $@
diff --git a/configure.ac b/configure.ac
index d7c57aa..d6eb0aa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -59,6 +59,23 @@ then
   fi
 fi
 
+if test x"$cross_compiling" = xyes; then
+    CC_FOR_BUILD="${CC_FOR_BUILD-gcc}"
+    CCLD_FOR_BUILD="${CCLD_FOR_BUILD-gcc}"
+    CFLAGS_FOR_BUILD="${CFLAGS_FOR_BUILD}"
+    LDFLAGS_FOR_BUILD="${LDFLAGS_FOR_BUILD}"
+else
+    CC_FOR_BUILD="${CC_FOR_BUILD-\$(CC)}"
+    CCLD_FOR_BUILD="${CCLD_FOR_BUILD-\$(CCLD)}"
+    CFLAGS_FOR_BUILD="${CFLAGS_FOR_BUILD-\$(CFLAGS)}"
+    LDFLAGS_FOR_BUILD="${LDFLAGS_FOR_BUILD-\$(LDFLAGS)}"
+fi
+AC_ARG_VAR(CC_FOR_BUILD, [build system C compiler])
+AC_ARG_VAR(CCLD_FOR_BUILD, [build system C linker frontend])
+AC_ARG_VAR(CFLAGS_FOR_BUILD, [build system C compiler arguments])
+AC_ARG_VAR(LDFLAGS_FOR_BUILD, [build system C linker frontend arguments])
+
+
 # Check for a 64-bit integer type
 AC_TYPE_INT64_T