elementary: build elementary_test additionally as shared object

For our exactness testing we are dlopen() the elementary_test
executable. Until glibc 2.30 this was posible with -pie, but it changed
in the glibc version. They no longer allow these executables to be
dlopen()'ed.

As a workaround for now we are building elementary_test also as a shared
object file which we load and use in the exactness testing process.

The code came from Marcel Hollerbach and I only tested it and fixed up a
small detail.

Differential Revision: https://phab.enlightenment.org/D11284

src/bin/elementary/meson.build

@@ -169,9 +169,11 @@ elementary_test_src = [
 
 if sys_windows == false
   link_args = ['-rdynamic', '-fPIC', '-pie']
+  link_args_lib = ['-rdynamic', '-fPIC']
   package_c_args =  package_c_args + ['-fPIC']
 else
   link_args = []
+  link_args_lib = []
 endif
 elementary_test = executable('elementary_test',
         elementary_test_src,
@@ -185,6 +187,18 @@ elementary_test = executable('elementary_test',
         link_args: link_args
 )
 
+library('elementary_test',
+        elementary_test_src,
+        dependencies: [elementary] + elementary_deps + elementary_pub_deps,
+        install: false,
+        c_args : package_c_args + [
+          '-Delementary_test_BIN_DIR="'+dir_bin+'"',
+          '-Delementary_test_LIB_DIR="'+dir_lib+'"',
+          '-Delementary_test_DATA_DIR="'+join_paths(dir_data,'elementary')+'"'
+        ],
+        link_args: link_args_lib
+)
+
 elementary_config_src = [
    'config.c'
 ]