msvcrt/tests: Use the C standard for multiline strings.

dlls/msvcrt/tests/file.c

diff --git a/dlls/msvcrt/tests/file.c b/dlls/msvcrt/tests/file.c
index 66a0035..0f235b5 100644
--- a/dlls/msvcrt/tests/file.c
+++ b/dlls/msvcrt/tests/file.c
@@ -320,15 +320,15 @@
     char ibuf[4];
     int i;
     static const char obuf[] =
-"00\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000000000000000000000000000000000000000000000000000000000000000\n\
-000000000000000000\n\
-1111111111111111111";
+"00\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000000000000000000000000000000000000000000000000000000000000000\n"
+"000000000000000000\n"
+"1111111111111111111";
 
     fp = fopen("ascii2.tst", "wt");
     fwrite(obuf, 1, sizeof(obuf), fp);