Skip a number of 'g++.dg/compat/' test cases for '-fno-exceptions' testing

Skip a number of 'g++.dg/compat/' test cases for '-fno-exceptions' testing

Running 'make check' with: 'RUNTESTFLAGS=--target_board=unix/-fno-exceptions',
'error: exception handling disabled' is triggered for C++ 'throw' etc. usage,
and per 'gcc/testsuite/lib/gcc-dg.exp:gcc-dg-prune':

    # If exceptions are disabled, mark tests expecting exceptions to be enabled
    # as unsupported.
    if { ![check_effective_target_exceptions_enabled] } {
        if [regexp "(^|\n)\[^\n\]*: error: exception handling disabled" $text] {
          return "::unsupported::exception handling disabled"
        }

..., which generally means:

    -PASS: [...] (test for excess errors)
    +UNSUPPORTED: [...]: exception handling disabled

However, this doesn't work for "split files" test cases.  For example:

    PASS: g++.dg/compat/eh/ctor1 cp_compat_main_tst.o compile
    [-PASS:-]{+UNSUPPORTED:+} g++.dg/compat/eh/ctor1 cp_compat_x_tst.o [-compile-]{+compile: exception handling disabled+}
    [-PASS:-]{+UNSUPPORTED:+} g++.dg/compat/eh/ctor1 cp_compat_y_tst.o [-compile-]{+compile: exception handling disabled+}
    [-PASS:-]{+UNRESOLVED:+} g++.dg/compat/eh/ctor1 cp_compat_x_tst.o-cp_compat_y_tst.o link
    [-PASS:-]{+UNRESOLVED:+} g++.dg/compat/eh/ctor1 cp_compat_x_tst.o-cp_compat_y_tst.o execute

The "compile"/"assemble" tests (either continue to work, or) result in the
expected 'UNSUPPORTED: [...] compile: exception handling disabled', but
dependent "link" and "execute" tests then turn UNRESOLVED.

Specify 'dg-require-effective-target exceptions_enabled' for those test cases.

	gcc/testsuite/
	* g++.dg/compat/eh/ctor1_main.C: Specify
	'dg-require-effective-target exceptions_enabled'.
	* g++.dg/compat/eh/ctor2_main.C: Likewise.
	* g++.dg/compat/eh/dtor1_main.C: Likewise.
	* g++.dg/compat/eh/filter1_main.C: Likewise.
	* g++.dg/compat/eh/filter2_main.C: Likewise.
	* g++.dg/compat/eh/new1_main.C: Likewise.
	* g++.dg/compat/eh/nrv1_main.C: Likewise.
	* g++.dg/compat/eh/spec3_main.C: Likewise.
	* g++.dg/compat/eh/template1_main.C: Likewise.
	* g++.dg/compat/eh/unexpected1_main.C: Likewise.
	* g++.dg/compat/init/array5_main.C: Likewise.