[libcxx] [test] Fix MSVC warning C4067 "unexpected tokens following preprocessor directive - expected a newline".

[STL_MSFT]

Summary

[libcxx] [test] Fix MSVC warning C4067 "unexpected tokens following preprocessor directive - expected a newline".

Also fixes Clang/LLVM 4.0 (for Windows) error "function-like macro 'TEST_GLIBC_PREREQ' is not defined".

[STL_MSFT]

Ping for this one - there's no functional change here, but since I don't have any glibc coverage, I wanted to get a review.

test/std/localization/locale.categories/category.monetary/locale.moneypunct.byname/curr_symbol.pass.cpp

int main()
         assert(f.curr_symbol() == L" EUR");
     }
 
     {
         Fnf f(LOCALE_ru_RU_UTF_8, 1);
         // GLIBC <= 2.23 uses currency_symbol="<U0440><U0443><U0431>"
         // GLIBC >= 2.24 uses currency_symbol="<U20BD>"
         // See also: http://www.fileformat.info/info/unicode/char/20bd/index.htm
-#if defined(TEST_GLIBC_PREREQ) && TEST_GLIBC_PREREQ(2, 24)
+#if defined(TEST_GLIBC_PREREQ)
+    #if TEST_GLIBC_PREREQ(2, 24)
+        #define TEST_GLIBC_2_24_CURRENCY_SYMBOL
+    #endif
+#endif
+
+#if defined(TEST_GLIBC_2_24_CURRENCY_SYMBOL)
         assert(f.curr_symbol() == " \u20BD");
 #else
         assert(f.curr_symbol() == " \xD1\x80\xD1\x83\xD0\xB1");
 #endif
     }
     {
         Fnt f(LOCALE_ru_RU_UTF_8, 1);
         assert(f.curr_symbol() == " RUB");
     }
     {
         Fwf f(LOCALE_ru_RU_UTF_8, 1);
-#if defined(TEST_GLIBC_PREREQ) && TEST_GLIBC_PREREQ(2, 24)
+#if defined(TEST_GLIBC_2_24_CURRENCY_SYMBOL)
         assert(f.curr_symbol() == L" \u20BD");
 #else
         assert(f.curr_symbol() == L" \x440\x443\x431");
 #endif
     }
 
     {
         Fwt f(LOCALE_ru_RU_UTF_8, 1);