gdb: fix dlfcn detection

fixes #1486

src/gdb.mk

@@ -8,7 +8,7 @@ $(PKG)_SUBDIR   := gdb-$($(PKG)_VERSION)
 $(PKG)_FILE     := gdb-$($(PKG)_VERSION).tar.xz
 $(PKG)_URL      := http://ftp.gnu.org/pub/gnu/$(PKG)/$($(PKG)_FILE)
 $(PKG)_URL_2    := ftp://ftp.cs.tu-berlin.de/pub/gnu/$(PKG)/$($(PKG)_FILE)
-$(PKG)_DEPS     := gcc expat libiconv readline zlib
+$(PKG)_DEPS     := gcc dlfcn-win32 expat libiconv readline zlib
 
 define $(PKG)_UPDATE
     $(WGET) -q -O- 'http://ftp.gnu.org/gnu/gdb/?C=M;O=D' | \
@@ -21,6 +21,7 @@ define $(PKG)_BUILD
     cd '$(1)' && ./configure \
         $(MXE_CONFIGURE_OPTS) \
         --with-system-readline \
+        host_configargs="LIBS=\"`$(TARGET)-pkg-config --libs dlfcn`\"" \
         CONFIG_SHELL=$(SHELL)
     $(MAKE) -C '$(1)' -j '$(JOBS)'