Do not export symbols from libs in libts

When the libts library is linked all of the symbols that come from other
static libraries that are linked to libts are exported by default. This
behaviour is undesired, since we want to control the public interface of
libts. Also it causes problems e.g. in the linux-pc deployment where the
MbedTLS static lib is linked into libts, making all psa_* symbols
exported. Fix the issue by adding the necessary linker option.

Link: https://sourceware.org/binutils/docs-2.40/ld.html#index-_002d_002dexclude_002dlibs
Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
Change-Id: I60fd376b274941cfc1d2ae29a2fb5634e446f6ce
diff --git a/deployments/libts/libts.cmake b/deployments/libts/libts.cmake
index bcae82b..9a1b9e1 100644
--- a/deployments/libts/libts.cmake
+++ b/deployments/libts/libts.cmake
@@ -49,6 +49,9 @@
 	EXPORT_PUBLIC_INTERFACE_SERVICE_LOCATOR
 )
 
+# Do not export symbols from static libraries linked to this library
+target_link_options(ts PRIVATE -Wl,--exclude-libs,ALL)
+
 #-------------------------------------------------------------------------------
 #  Export the library and the corresponding public interface header files
 #