shared/format-table: do not print '.0'

This makes output a bit shorter and nicer. For us, shorter output is generally
better.

Also, drop unnecessary UINT64_C macros. The left operand is always uint64_t,
and C upcasting rules mean that it doesn't matter if the right operand is
narrower or signed, the operation is always done on the wider unsigned type.

test/units/TEST-58-REPART.sh

@@ -435,7 +435,7 @@ EOF
 		"offset" : 1048576,
 		"old_size" : 0,
 		"raw_size" : 33554432,
-		"size" : "-> 32.0M",
+		"size" : "-> 32M",
 		"old_padding" : 0,
 		"raw_padding" : 0,
 		"padding" : "-> 0B",
@@ -496,7 +496,7 @@ EOF
 		"offset" : 1048576,
 		"old_size" : 0,
 		"raw_size" : 33554432,
-		"size" : "-> 32.0M",
+		"size" : "-> 32M",
 		"old_padding" : 0,
 		"raw_padding" : 0,
 		"padding" : "-> 0B",
@@ -512,7 +512,7 @@ EOF
 		"offset" : 34603008,
 		"old_size" : 0,
 		"raw_size" : 33554432,
-		"size" : "-> 32.0M",
+		"size" : "-> 32M",
 		"old_padding" : 0,
 		"raw_padding" : 0,
 		"padding" : "-> 0B",