libexif: add patch to avoid building docs

Signed-off-by: W. Michael Petullo <mike@flyn.org>

libs/libexif/patches/100-no_doc.patch

@@ -1,11 +1,12 @@
---- a/Makefile.in
-+++ b/Makefile.in
-@@ -280,7 +280,7 @@ target_alias = @target_alias@
+diff -u --recursive libexif-0.6.21-vanilla/Makefile.in libexif-0.6.21/Makefile.in
+--- libexif-0.6.21-vanilla/Makefile.in	2014-07-17 22:17:52.439423287 -0400
++++ libexif-0.6.21/Makefile.in	2014-07-17 22:18:28.125359945 -0400
+@@ -289,7 +289,7 @@
  top_build_prefix = @top_build_prefix@
  top_builddir = @top_builddir@
  top_srcdir = @top_srcdir@
 -SUBDIRS = m4m po libexif test doc binary contrib
 +SUBDIRS = m4m po libexif test binary contrib
- @SHIP_BINARIES_TRUE@README_W32_XDIST = README-Win32.txt
- EXTRA_DIST = @PACKAGE_TARNAME@.spec $(README_W32_XDIST) libexif.pc.in \
+ EXTRA_DIST = @PACKAGE_TARNAME@.spec README-Win32.txt libexif.pc.in \
  	libexif-uninstalled.pc.in
+ pkgconfigdir = $(libdir)/pkgconfig