syntax: functions require return type. remove `->`

The purpose of this is:

 * Only one way to do things
 * Changing a function with void return type to return a possible
   error becomes a 1 character change, subtly encouraging
   people to use errors.

See #632

Here are some imperfect sed commands for performing this update:

remove arrow:

```
sed -i 's/\(\bfn\b.*\)-> /\1/g' $(find . -name "*.zig")
```

add void:

```
sed -i 's/\(\bfn\b.*\))\s*{/\1) void {/g' $(find ../ -name "*.zig")
```

Some cleanup may be necessary, but this should do the bulk of the work.

1 files changed, 3 insertions, 3 deletions

diff --git a/std/math/tanh.zig b/std/math/tanh.zig
index 8560538cdf..c1f5a0ca46 100644
--- a/std/math/tanh.zig
+++ b/std/math/tanh.zig
@@ -10,7 +10,7 @@ const math = std.math;
 const assert = std.debug.assert;
 const expo2 = @import("expo2.zig").expo2;
 
-pub fn tanh(x: var) -> @typeOf(x) {
+pub fn tanh(x: var) @typeOf(x) {
     const T = @typeOf(x);
     return switch (T) {
         f32 => tanh32(x),
@@ -22,7 +22,7 @@ pub fn tanh(x: var) -> @typeOf(x) {
 // tanh(x) = (exp(x) - exp(-x)) / (exp(x) + exp(-x))
 //         = (exp(2x) - 1) / (exp(2x) - 1 + 2)
 //         = (1 - exp(-2x)) / (exp(-2x) - 1 + 2)
-fn tanh32(x: f32) -> f32 {
+fn tanh32(x: f32) f32 {
     const u = @bitCast(u32, x);
     const ux = u & 0x7FFFFFFF;
     const ax = @bitCast(f32, ux);
@@ -66,7 +66,7 @@ fn tanh32(x: f32) -> f32 {
     }
 }
 
-fn tanh64(x: f64) -> f64 {
+fn tanh64(x: f64) f64 {
     const u = @bitCast(u64, x);
     const w = u32(u >> 32);
     const ax = @bitCast(f64, u & (@maxValue(u64) >> 1));