python: enable shared python lib; make this the norm

This will reduce the bloat when users will want to compile in their
Python C extensions.
There will be a initial bloat (several kb) if just Python
is installed, but that will be compensated when users will add more
C extensions.

During the build we also have to add Python's PKG_BUILD_DIR
so that the shared lib is found when compiling Python's
built-in C extensions.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/Makefile

@@ -140,7 +140,7 @@ MAKE_FLAGS:=\
 	DESTDIR="$(PKG_INSTALL_DIR)" \
 	CROSS_COMPILE=yes \
 	CFLAGS="$(TARGET_CFLAGS) -DNDEBUG -fno-inline" \
-	LDFLAGS="$(TARGET_LDFLAGS)" \
+	LDFLAGS="$(TARGET_LDFLAGS) -L$(PKG_BUILD_DIR)" \
 	LD="$(TARGET_CC)" \
 	PGEN=pgen2
 
@@ -155,7 +155,7 @@ define Build/Configure
 	$(CP) ./files/config.site $(PKG_BUILD_DIR)
 	$(call Build/Configure/Default, \
 		--sysconfdir=/etc \
-		--disable-shared \
+		--enable-shared \
 		--without-cxx-main \
 		--with-threads \
 		--with-system-ffi="$(STAGING_DIR)/usr" \
@@ -176,7 +176,7 @@ define Build/InstallDev
 		$(1)/usr/include/
 	$(CP) \
 		$(STAGING_DIR_HOST)/lib/python$(PYTHON_VERSION) \
-		$(PKG_BUILD_DIR)/libpython$(PYTHON_VERSION).a \
+		$(PKG_BUILD_DIR)/libpython$(PYTHON_VERSION).so* \
 		$(1)/usr/lib/
 	$(CP) \
 		$(PKG_INSTALL_DIR)/usr/lib/python$(PYTHON_VERSION)/config \
@@ -389,6 +389,7 @@ endef
 define PyPackage/python/install
 	$(LN) python$(PYTHON_VERSION) $(1)/usr/bin/python
 	$(LN) python$(PYTHON_VERSION) $(1)/usr/bin/python2
+	$(CP) $(PKG_BUILD_DIR)/libpython$(PYTHON_VERSION).so* $(1)/usr/lib/
 endef
 
 define PyPackage/python-doc/filespec