add lua.pc

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
[Jörg Krause: add @MYLIBS@]
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>

Index: b/etc/lua.pc
===================================================================
--- /dev/null
+++ b/etc/lua.pc
@@ -0,0 +1,31 @@
+# lua.pc -- pkg-config data for Lua
+
+# vars from install Makefile
+
+# grep '^V=' ../Makefile
+V= 5.3
+# grep '^R=' ../Makefile
+R= 5.3.4
+
+# grep '^INSTALL_.*=' ../Makefile | sed 's/INSTALL_TOP/prefix/'
+prefix= /usr
+INSTALL_BIN= ${prefix}/bin
+INSTALL_INC= ${prefix}/include
+INSTALL_LIB= ${prefix}/lib
+INSTALL_MAN= ${prefix}/man/man1
+INSTALL_LMOD= ${prefix}/share/lua/${V}
+INSTALL_CMOD= ${prefix}/lib/lua/${V}
+
+# canonical vars
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: Lua
+Description: An Extensible Extension Language
+Version: ${R}
+Requires:
+Libs: -L${libdir} -llua -lm @MYLIBS@
+Cflags: -I${includedir}
+
+# (end of lua.pc)