libphobos: Organize druntime and phobos tests under common directory

The druntime and druntime_shared tests are identical, save for one
compiled with `-static-libphobos' and the other `-shared-libphobos'.
Move them to libphobos.druntime/static and libphobos.druntime/shared
respectively.  This has also been done for libphobos.phobos.

libphobos/ChangeLog:

	* testsuite/libphobos.druntime_shared/druntime_shared.exp: Move to...
	* testsuite/libphobos.druntime/shared/druntime-shared.exp: ...here.
	* testsuite/libphobos.druntime/druntime.exp: Move to...
	* testsuite/libphobos.druntime/static/druntime-static.exp: ...here.
	* testsuite/libphobos.phobos_shared/phobos_shared.exp: Move to...
	* testsuite/libphobos.phobos/shared/phobos-shared.exp: ...here.
	* testsuite/libphobos.phobos/phobos.exp: Move to...
	* testsuite/libphobos.phobos/static/phobos-static.exp: ...here.

libphobos/testsuite/libphobos.phobos_shared/phobos_shared.exp → libphobos/testsuite/libphobos.phobos/shared/phobos-shared.exp

@@ -35,10 +35,10 @@ if { [is-effective-target linux_pre_2639] } {
 
 set libphobos_skip_tests {
     # Skip curl tests if library is not available
-    { libphobos.phobos_shared/etc/c/curl.d { ! libcurl_available } }
-    { libphobos.phobos_shared/std/net/curl.d { ! libcurl_available } }
+    { libphobos.phobos/shared/etc/c/curl.d { ! libcurl_available } }
+    { libphobos.phobos/shared/std/net/curl.d { ! libcurl_available } }
     # Skip concurrency.d test: SEGVs or hangs on macOS 13+ (PR d/111628).
-    { libphobos.phobos_shared/std/concurrency.d { x86_64-apple-darwin2[2-9]* } }
+    { libphobos.phobos/shared/std/concurrency.d { x86_64-apple-darwin2[2-9]* } }
 }
 
 # Initialize dg.

libphobos/testsuite/libphobos.phobos/phobos.exp → libphobos/testsuite/libphobos.phobos/static/phobos-static.exp

@@ -35,10 +35,10 @@ if { [is-effective-target linux_pre_2639] } {
 
 set libphobos_skip_tests {
     # Skip curl tests if library is not available
-    { libphobos.phobos/etc/c/curl.d { ! libcurl_available } }
-    { libphobos.phobos/std/net/curl.d { ! libcurl_available } }
+    { libphobos.phobos/static/etc/c/curl.d { ! libcurl_available } }
+    { libphobos.phobos/static/std/net/curl.d { ! libcurl_available } }
     # Skip concurrency.d test: SEGVs or hangs on macOS 13+ (PR d/111628).
-    { libphobos.phobos/std/concurrency.d { x86_64-apple-darwin2[2-9]* } }
+    { libphobos.phobos/static/std/concurrency.d { x86_64-apple-darwin2[2-9]* } }
 }
 
 # Initialize dg.