Add the compilation of a shared library.
Compile the lua binary with the shared library.
And install the shared library.
The variable BUILDMODE allows to switch between static and dynamic mode.

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>

Index: b/Makefile
===================================================================
--- a/Makefile
+++ b/Makefile
@@ -42,6 +42,7 @@
 TO_BIN= lua luac
 TO_INC= lua.h luaconf.h lualib.h lauxlib.h lua.hpp
 TO_LIB= liblua.a
+TO_SOLIB = liblua.so.$(R)
 TO_MAN= lua.1 luac.1
 
 # Lua version and release.
@@ -60,6 +61,8 @@
 install: dummy
 	cd src && $(MKDIR) $(INSTALL_BIN) $(INSTALL_INC) $(INSTALL_LIB) $(INSTALL_MAN) $(INSTALL_LMOD) $(INSTALL_CMOD)
 	cd src && $(INSTALL_EXEC) $(TO_BIN) $(INSTALL_BIN)
+	test -f src/$(TO_SOLIB) && cd src && $(INSTALL_EXEC) $(TO_SOLIB) $(INSTALL_LIB) || :
+	test -f src/$(TO_SOLIB) && ln -sf $(TO_SOLIB) $(INSTALL_LIB)/liblua.so || :
 	cd src && $(INSTALL_DATA) $(TO_INC) $(INSTALL_INC)
 	cd src && $(INSTALL_DATA) $(TO_LIB) $(INSTALL_LIB)
 	cd doc && $(INSTALL_DATA) $(TO_MAN) $(INSTALL_MAN)
Index: b/src/Makefile
===================================================================
--- a/src/Makefile
+++ b/src/Makefile
@@ -29,6 +29,7 @@
 PLATS= aix bsd c89 freebsd generic linux macosx mingw posix solaris
 
 LUA_A=	liblua.a
+LUA_SO=	liblua.so
 CORE_O=	lapi.o lcode.o lctype.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o \
 	lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o \
 	ltm.o lundump.o lvm.o lzio.o
@@ -43,8 +44,13 @@
 LUAC_O=	luac.o
 
 ALL_O= $(BASE_O) $(LUA_O) $(LUAC_O)
+ifneq (dynamic,$(BUILDMODE))
 ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T)
+else
+ALL_T= $(LUA_A) $(LUA_SO) $(LUA_T) $(LUAC_T)
+endif
 ALL_A= $(LUA_A)
+ALL_SO= $(LUA_SO)
 
 # Targets start here.
 default: $(PLAT)
@@ -55,12 +61,23 @@
 
 a:	$(ALL_A)
 
+so:	$(ALL_SO)
+
 $(LUA_A): $(BASE_O)
 	$(AR) $@ $(BASE_O)
 	$(RANLIB) $@
 
+$(LUA_SO): $(CORE_O) $(LIB_O)
+	$(CC) -o $@.$(PKG_VERSION) -shared -Wl,-soname="$@.$(PKG_VERSION)" $?
+	ln -fs $@.$(PKG_VERSION) $@
+
+ifneq (dynamic,$(BUILDMODE))
 $(LUA_T): $(LUA_O) $(LUA_A)
 	$(CC) -o $@ $(LDFLAGS) $(LUA_O) $(LUA_A) $(LIBS)
+else
+$(LUA_T): $(LUA_O) $(LUA_SO)
+	$(CC) -o $@ -L. $(LDFLAGS) $(LUA_O) -llua $(LIBS)
+endif
 
 $(LUAC_T): $(LUAC_O) $(LUA_A)
 	$(CC) -o $@ $(LDFLAGS) $(LUAC_O) $(LUA_A) $(LIBS)