std lib: modify allocator idiom

Before we accepted a nullable allocator for some stuff like
opening files. Now we require an allocator.

Use the mem.FixedBufferAllocator pattern if a bound on the amount
to allocate is known.

This also establishes the pattern that usually an allocator is the
first argument to a function (possibly after "self").

fix docs for std.cstr.addNullByte

self hosted compiler:
 * only build docs when explicitly asked to
 * clean up main
 * stub out zig fmt

1 files changed, 1 insertions, 2 deletions

diff --git a/std/cstr.zig b/std/cstr.zig
index 86d59b11dd..f905b57c91 100644
--- a/std/cstr.zig
+++ b/std/cstr.zig
@@ -39,8 +39,7 @@ fn testCStrFnsImpl() void {
     assert(len(c"123456789") == 9);
 }
 
-/// Returns a mutable slice with exactly the same size which is guaranteed to
-/// have a null byte after it.
+/// Returns a mutable slice with 1 more byte of length which is a null byte.
 /// Caller owns the returned memory.
 pub fn addNullByte(allocator: &mem.Allocator, slice: []const u8) ![]u8 {
     const result = try allocator.alloc(u8, slice.len + 1);