tests: emscripten doesn't support common symbols, so skip COMMON tests

clang (as of v12.0.0) throws an error on the __attribute__((common)) in the
produced .c so these tests prevented building fbc-tests. Emscripten doesn't
support it with -sWASM=0 either, because that still first compiles to wasm .o
files. There's apparently no plan to support common symbols in wasm.

A couple of the tests in namespace/redim-3.bas are kludged to compile but fail.

tests/dim/common-shared-1.bas

@@ -1,5 +1,8 @@
 #include "fbcunit.bi"
 
+'' Emscripten (and wasm) doesn't support common symbols
+#ifndef __FB_JS__
+
 #include "common-shared.bi"
 
 '' COMMON SHARED in the global namespace test
@@ -73,3 +76,5 @@ SUITE( fbc_tests.dim_.common_shared_1 )
 		shadowingACommon.test_proc
 	END_TEST
 END_SUITE
+
+#endif

tests/dim/common-shared-2.bas

@@ -1,5 +1,8 @@
 #include "fbcunit.bi"
 
+'' Emscripten (and wasm) doesn't support common symbols
+#ifndef __FB_JS__
+
 #include "common-shared.bi"
 
 '' COMMON SHARED in the global namespace test
@@ -16,3 +19,5 @@ sub commonShared2Checks( )
 	CU_ASSERT( lbound( arrayi5 ) = 5 ) : CU_ASSERT( ubound( arrayi5 ) = 5 )
 	CU_ASSERT( lbound( arrayi6 ) = 6 ) : CU_ASSERT( ubound( arrayi6 ) = 6 )
 end sub
+
+#endif

tests/dim/redim.bas

@@ -78,6 +78,9 @@ SUITE( fbc_tests.dim_.redim_ )
 		END_TEST
 	END_TEST_GROUP
 
+	'' Emscripten (and wasm) doesn't support common symbols
+	#ifndef __FB_JS__
+
 	'' Regression test for #3474348
 	TEST_GROUP( commonRedimRedim )
 		common array() as integer
@@ -115,6 +118,8 @@ SUITE( fbc_tests.dim_.redim_ )
 		END_TEST
 	END_TEST_GROUP
 
+	#endif
+
 	'' Regression test for #3510684: An array using a different mangling, which
 	'' affects the array descriptor too -- should still work just the same.
 	extern "C"

tests/namespace/redim-3.bas

@@ -1,5 +1,11 @@
 #include "fbcunit.bi"
 
+'' Emscripten (and wasm) doesn't support common symbols
+#ifdef __FB_JS__
+	#undef common
+	#define common dim  '' Fixes the compile but fails tests
+#endif
+
 common shared array1() as integer
 common shared array2() as integer
 dim shared array3() as integer