Embed DATDIR make variable value into yosys binary.

Use it as the last resort in the share/ directory location search.

Makefile

@@ -281,6 +281,7 @@ $(eval $(call add_include_file,backends/ilang/ilang_backend.h))
 
 OBJS += kernel/driver.o kernel/register.o kernel/rtlil.o kernel/log.o kernel/calc.o kernel/yosys.o kernel/cellaigs.o
 kernel/log.o: CXXFLAGS += -DYOSYS_SRC='"$(YOSYS_SRC)"'
+kernel/yosys.o: CXXFLAGS += -DYOSYS_DATDIR='"$(DATDIR)"'
 
 OBJS += libs/bigint/BigIntegerAlgorithms.o libs/bigint/BigInteger.o libs/bigint/BigIntegerUtils.o
 OBJS += libs/bigint/BigUnsigned.o libs/bigint/BigUnsignedInABase.o

kernel/yosys.cc

@@ -701,6 +701,11 @@ std::string proc_share_dirname()
 	proc_share_path = proc_self_path + "../share/yosys/";
 	if (check_file_exists(proc_share_path, true))
 		return proc_share_path;
+#    ifdef YOSYS_DATDIR
+	proc_share_path = YOSYS_DATDIR "/";
+	if (check_file_exists(proc_share_path, true))
+		return proc_share_path;
+#    endif
 #  endif
 	log_error("proc_share_dirname: unable to determine share/ directory!\n");
 }