Added CPack packaging and fix Linux compatibility.

- configure wrapper had bash syntax some places; replaced w/ sh syntax
- Added FindOpenSSL module.  The one that ships with CMake does not
  allow for specifying a non-standard location.
- datadir configure option changed to be relative to prefix.  This
  simplifies the packaging from having to consider absolute paths.
- Added macro for changing install_name of shared libs that need to
  ship with precompiled Bro for OS X.  This is only the optional
  libmagic and libGeoIP for now.

cmake/SetPackageFileName.cmake

@@ -0,0 +1,18 @@
+# Sets CPACK_PACKAGE_FILE name in the following format:
+#
+# <project_name>-<version>-<OS/platform>-<arch>
+#
+# The version must already be set in the VERSION variable
+
+set(CPACK_PACKAGE_FILE_NAME "${CMAKE_PROJECT_NAME}-${VERSION}")
+set(CPACK_PACKAGE_FILE_NAME "${CPACK_PACKAGE_FILE_NAME}-${CMAKE_SYSTEM_NAME}")
+if (APPLE)
+    # Only Intel-based Macs are supported.  CMAKE_SYSTEM_PROCESSOR may
+    # return the confusing 'i386' if running a 32-bit kernel, but chances
+    # are the binary is x86_64 (or more generally 'Intel') compatible.
+    set(arch "Intel")
+else ()
+    set (arch ${CMAKE_SYSTEM_PROCESSOR})
+endif ()
+
+set(CPACK_PACKAGE_FILE_NAME "${CPACK_PACKAGE_FILE_NAME}-${arch}")