fix target-c-int-width

Newer rustc versions require this value to be an integer.

For more information see #509.

Author: Freax13

example-kernel/x86_64-example-kernel.json

@@ -4,7 +4,7 @@
     "arch": "x86_64",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
+    "target-c-int-width": 32,
     "os": "none",
     "executables": true,
     "linker-flavor": "ld.lld",

test-kernel/x86_64-test-kernel.json

@@ -4,7 +4,7 @@
     "arch": "x86_64",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
+    "target-c-int-width": 32,
     "os": "none",
     "executables": true,
     "linker-flavor": "ld.lld",

x86_64-bootloader.json

@@ -11,7 +11,7 @@
     },
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
+    "target-c-int-width": 32,
     "arch": "x86_64",
     "os": "none",
     "features": "-mmx,-sse,+soft-float",