Build external libs statically in the DISABLE_DYNLOADING case

Fixes build for iOS.

In theory, it is a bit unclear whether DISABLE_DYNLOADING means to 1)
not build any dynamic libraries at all, not even of bundled 3rd-party
libraries, or 2) not build any own dynamic libraries, including
dynamically loaded UNO components, while still building 3rd-party
libraries as dynamic. But in practice, a use case for the latter is
nonexistent, nobody uses --disable-dynamic-loading in their
autogen.input, and DISABLE_DYNLOADING is turned on automatically for
iOS and Android.

What we want for iOS, for an LO-based app, is to not build any dynamic
libraries at all, but produce a single executable. Correspondingly for
Android, at least currently, we want to produce a single dynamic
library.

Change-Id: I7af4c3e53b13439612bb57bbb0fc8b118bda96bd

external/librevenge/ExternalProject_librevenge.mk

@@ -26,8 +26,9 @@ $(call gb_ExternalProject_get_state_target,librevenge,build) :
 		export PKG_CONFIG="" \
 		&& ./configure \
 			--with-pic \
-			--enable-shared \
-			--disable-static \
+			$(if $(DISABLE_DYNLOADING), \
+				--disable-shared --enable-static, \
+				--enable-shared --disable-static) \
 			$(if $(ENABLE_DEBUG),--enable-debug,--disable-debug) \
 			--disable-werror \
 			--disable-weffc \

external/libwpd/ExternalProject_libwpd.mk

@@ -24,8 +24,9 @@ $(call gb_ExternalProject_get_state_target,libwpd,build) :
 		export PKG_CONFIG="" \
 		&& MAKE=$(MAKE) ./configure \
 			--with-pic \
-			--enable-shared \
-			--disable-static \
+			$(if $(DISABLE_DYNLOADING), \
+				--disable-shared --enable-static, \
+				--enable-shared --disable-static) \
 			--without-docs \
 			--disable-tools \
 			--disable-debug \

external/libwpg/ExternalProject_libwpg.mk

@@ -25,8 +25,9 @@ $(call gb_ExternalProject_get_state_target,libwpg,build) :
 		export PKG_CONFIG="" \
 		&& MAKE=$(MAKE) ./configure \
 			--with-pic \
-			--enable-shared \
-			--disable-static \
+			$(if $(DISABLE_DYNLOADING), \
+				--disable-shared --enable-static, \
+				--enable-shared --disable-static) \
 			--without-docs \
 			--disable-tools \
 			--disable-debug \