djvulibre: enable shared targets

Patch "fix linking errors in shared builds" fixes i686-w64-mingw32.shared.

Change of djvulibre.mk fixes x86_64-w64-mingw32.shared by changing deplibs
check method to "objdump". See the explanations below.
On Wheezy (at least) "file" returns "data" for x86-64 object files from
libmsvcp60.a. Therefore the check fails with the following message:

*** Warning: linker path does not have real file for library -lmsvcp60.
*** I have the capability to make that library automatically link in when
*** you link to this library.  But I can only do this if you have a
*** shared version of the library, which you do not appear to have
*** because I did check the linker path looking for a file starting
*** with libmsvcp60 and none of the candidates passed a file format test
*** using a file magic. Last file checked: /home/mxe/mxe-djvulibre/usr/lib/gcc/x86_64-w64-mingw32.shared/4.9.3/../../../../x86_64-w64-mingw32.shared/lib//libmsvcp60.a
*** The inter-library dependencies that have been dropped here will be
*** automatically added whenever a program is linked with this library
*** or is declared to -dlopen it.

*** Since this library must not contain undefined symbols,
*** because either the platform does not support them or
*** it was explicitly requested with -no-undefined,
*** libtool will only create a static version of it.

Then it compiled static library and failed when compiling djvulibre-test.c
because of missing -ljpeg.

2 files changed, 34 insertions, 4 deletions

diff --git a/src/djvulibre-1-fixes.patch b/src/djvulibre-1-fixes.patch
index eba6e5e..b19b52c 100644
--- a/src/djvulibre-1-fixes.patch
+++ b/src/djvulibre-1-fixes.patch
@@ -279,3 +279,33 @@ index 1111111..2222222 100644
      p += 1;
    // Cast and return
    return (short**)p;
+
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Boris Nagaev <bnagaev@gmail.com>
+Date: Sun, 10 Apr 2016 14:58:05 +0200
+Subject: [PATCH] fix linking errors in shared builds
+
+> the presence
+> of any one __declspec(dllexport) in any object file disables the
+> auto-export feature, so if you declare any symbol dllexport you have to
+> mark them all (or explicily -Wl,--export-all-symbols.)
+
+See http://mingw-users.1079350.n2.nabble.com/MinGW-produces-incorrect-dll-a-files-tp1109211p1109231.html
+
+./configure adds -Wl,--export-all-symbols if host matches "*-mingw32",
+but MXE's host is "i686-w64-mingw32.shared". This patch changes the
+pattern to "*-mingw32*".
+
+diff --git a/configure b/configure
+index 1111111..2222222 100755
+--- a/configure
++++ b/configure
+@@ -2927,7 +2927,7 @@ DLLFLAGS=
+ 
+ # Special cases
+ case "$host" in
+-  *-mingw32)
++  *-mingw32*)
+      DLLFLAGS="$DLLFLAGS -Wl,--export-all-symbols"
+      LIBS=-lmsvcp60
+   ;;
diff --git a/src/djvulibre.mk b/src/djvulibre.mk
index 8827123..3e4e09a 100644
--- a/src/djvulibre.mk
+++ b/src/djvulibre.mk
@@ -20,7 +20,10 @@ endef
 define $(PKG)_BUILD
     cd '$(1)' && CPPFLAGS='-DDLL_EXPORT' ./configure \
         $(MXE_CONFIGURE_OPTS) \
-        --disable-desktopfiles
+        --disable-desktopfiles \
+        $(if $(BUILD_SHARED),\
+            lt_cv_deplibs_check_method='file_magic file format (pe-i386|pe-x86-64)' \
+            lt_cv_file_magic_cmd='$$OBJDUMP -f')
     $(MAKE) -C '$(1)' -j '$(JOBS)'
     $(MAKE) -C '$(1)/libdjvu' -j 1 install-lib \
         install-include install-pkgconfig
@@ -30,6 +33,3 @@ define $(PKG)_BUILD
         '$(2).c' -o '$(PREFIX)/$(TARGET)/bin/test-$(PKG).exe' \
         `'$(TARGET)-pkg-config' ddjvuapi --libs`
 endef
-
-$(PKG)_BUILD_SHARED =
-