[libc] Enable wide-read memory operations by default on Linux

Summary:
This patch changes the linux build to use the wide reads on the memory
operations by default. These memory functions will now potentially read
outside of the bounds explicitly allowed by the current function. While
technically undefined behavior in the standard, plenty of C library
implementations do this. it will not cause a segmentation fault on linux
as long as you do not cross a page boundary, and because we are only
*reading* memory it should not have atomic effects.

Author: jhuber6

libc/config/linux/config.json

@@ -0,0 +1,7 @@
+{
+  "string": {
+    "LIBC_CONF_STRING_UNSAFE_WIDE_READ": {
+      "value": true
+    }
+  }
+}