depends: always set CMAKE_POSITION_INDEPENDENT_CODE=ON

Rather than potentially having to set this per-package, set it globally,
as this should always be what we want. Without doing this, changes in
later commits will have to add this per-package.

Similar to https://github.com/bitcoin/bitcoin/pull/29488, which is the
Autotools equivalent.

depends/funcs.mk

@@ -181,6 +181,7 @@ $(1)_cmake=env CC="$$($(1)_cc)" \
                LDFLAGS="$$($(1)_ldflags)" \
                cmake -DCMAKE_INSTALL_PREFIX:PATH="$$($($(1)_type)_prefix)" \
                -DCMAKE_INSTALL_LIBDIR=lib/ \
+               -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
                $$($(1)_config_opts)
 ifeq ($($(1)_type),build)
 $(1)_cmake += -DCMAKE_INSTALL_RPATH:PATH="$$($($(1)_type)_prefix)/lib"