Remove if/loop tests, and a fastcomp test (#20897)

Removes the silliest tests we had: a single loop, a single if, and an if-else.

Also remove test_multiply_defined_symbols which only made sense in
fastcomp. There are no actually multiply defined symbols in that test, aside
from during the link stage, so this tested that the fastcomp .a linker handled
that properly. But lld does that today, and does not need testing here. Even
if we did want to test it, this is a poor test as the duplicate symbols are not
referred to anyhow, so they are not even collected from the respective .a
files.

Author: kripken

test/core/test_if.c

@@ -780,46 +780,6 @@ def test_rounding(self):
     self.set_setting('EXIT_RUNTIME')
     self.do_core_test('test_rounding.c')
 
-  def test_multiply_defined_symbols(self):
-    create_file('a1.c', 'int f() { return 1; }')
-    create_file('a2.c', 'void x() {}')
-    create_file('b1.c', 'int f() { return 2; }')
-    create_file('b2.c', 'void y() {}')
-    create_file('main.c', r'''
-      #include <stdio.h>
-      int f();
-      int main() {
-        printf("result: %d\n", f());
-        return 0;
-      }
-    ''')
-
-    self.emcc('a1.c', ['-c'])
-    self.emcc('a2.c', ['-c'])
-    self.emcc('b1.c', ['-c'])
-    self.emcc('b2.c', ['-c'])
-    self.emcc('main.c', ['-c'])
-
-    building.emar('cr', 'liba.a', ['a1.o', 'a2.o'])
-    building.emar('cr', 'libb.a', ['b1.o', 'b2.o'])
-
-    # Add -Wno-deprecated to avoid warning about bitcode linking in the LTO
-    # version of this test.
-    self.run_process([EMCC, '-r', '-o', 'all.o', 'main.o', 'liba.a', 'libb.a',
-                      '-Wno-deprecated'] + self.get_emcc_args())
-
-    self.emcc('all.o', output_filename='all.js')
-    self.do_run('all.js', 'result: 1', no_build=True)
-
-  def test_if(self):
-    self.do_core_test('test_if.c')
-
-  def test_if_else(self):
-    self.do_core_test('test_if_else.c')
-
-  def test_loop(self):
-    self.do_core_test('test_loop.c')
-
   def test_stack(self):
     self.set_setting('INLINING_LIMIT')
     # some extra coverage in all test suites for stack checks