unit: Fix Clang 8 "-Wstring-plus-int" warning

Declare the fixed string in unit/test-checksum.c as a static array instead of a string literal to address a warning exhibited by Clang 8 regarding addition of an integer to a string:

unit/test-checksum.c:170:30: warning: adding 'unsigned long' to a

      string does not append to the string [-Wstring-plus-int]
        iov[1].iov_base = FIXED_STR + FIXED_LEN / 2;
                          ~~~~~~~~~~^~~~~~~~~~~~~~~
unit/test-checksum.c:170:30: note: use array indexing to silence this
      warning
        iov[1].iov_base = FIXED_STR + FIXED_LEN / 2;
                                    ^
                          &         [              ]

Storing the string in an array makes it obvious that pointer arithmetic is being performed.

---
 unit/test-checksum.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

index 296395f..f21d0bb 100644
@@ -28,10 +28,12 @@
 
 #include <ell/ell.h>
 
-#define FIXED_STR  "The quick brown fox jumps over the lazy dog. " \
-		   "Jackdaws love my big sphinx of quartz. "       \
-		   "Pack my box with five dozen liquor jugs. "     \
-		   "How razorback-jumping frogs can level six piqued gymnasts!"
+static char FIXED_STR[] =
+	"The quick brown fox jumps over the lazy dog. "
+	"Jackdaws love my big sphinx of quartz. "
+	"Pack my box with five dozen liquor jugs. "
+	"How razorback-jumping frogs can level six piqued gymnasts!";
+
 #define FIXED_LEN  (strlen (FIXED_STR))
 
 static void test_unsupported(const void *data)

2.20.1

Hi Ossama,

Applied, thanks.

Regards,
-Denis