revert all changes regarding --exclude-libs,libcrypto.a

I don't have time right now to investigate the impact of this change

cmake/AwsCFlags.cmake

@@ -159,6 +159,20 @@ function(aws_set_common_properties target)
         # This becomes a define in config.h
         set(AWS_HAVE_POSIX_LARGE_FILE_SUPPORT ${HAS_LFS} CACHE BOOL "Posix Large File Support")
 
+        # Hide symbols from libcrypto.a
+        # This avoids problems when an application ends up using both libcrypto.a and libcrypto.so.
+        #
+        # An example of this happening is the aws-c-io tests.
+        # All the C libs are compiled statically, but then a PKCS#11 library is
+        # loaded at runtime which happens to use libcrypto.so from OpenSSL.
+        # If the symbols from libcrypto.a aren't hidden, then SOME function calls use the libcrypto.a implementation
+        # and SOME function calls use the libcrypto.so implementation, and this mismatch leads to weird crashes.
+        if (UNIX AND NOT APPLE)
+            # If we used target_link_options() (CMake 3.13+) we could make these flags PUBLIC
+            set_property(TARGET ${target} APPEND_STRING PROPERTY LINK_FLAGS " -Wl,--exclude-libs,libcrypto.a")
+        endif()
+
+
     endif()
 
     check_include_file(stdint.h HAS_STDINT)