Set errno when out of range in strtoimax (#111)

tool/build/calculator.c

@@ -443,7 +443,7 @@ bool ConsumeLiteral(const char *literal) {
   char *e;
   struct Value x;
   x.t = kInt;
-  x.i = strtoimax(literal, &e, 0);
+  x.i = *literal == '-' ? strtoimax(literal, &e, 0) : strtoumax(literal, &e, 0);
   if (!e || *e) {
     x.t = kFloat;
     x.f = strtod(literal, &e);

tool/build/calculator.ctest

@@ -81,3 +81,11 @@ false false || ! assert
 1 -1 min -1 = assert
 1 2 min 1 = assert
 rand64 rand64 rand64 rand64 != != && assert
+
+# HEX SIGN
+ -0x80000000 -2147483648 = assert
+  0x80000000  2147483648 = assert
+  0x80000001  2147483649 = assert
+  0xffffffff  4294967295 = assert
+ 0x100000000  4294967296 = assert
+-0x100000000 -4294967296 = assert