Produce a shared library instead of a static archive.

Signed-off-by: Lucas C. Villa Real <lucasvr@gobolinux.org>

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ff99fff..540cbd5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,7 @@ FILE(GLOB SNOWBALL_SOURCES
   libstemmer/libstemmer.c
 )
 
-ADD_LIBRARY(stemmer ${SNOWBALL_SOURCES})
+ADD_LIBRARY(stemmer SHARED ${SNOWBALL_SOURCES})
 
 INSTALL(TARGETS stemmer DESTINATION lib)
 INSTALL(FILES include/libstemmer.h DESTINATION include)