[libc] Fix typos in documentation

Author: kazutakahirata

libc/docs/gpu/testing.rst

@@ -7,7 +7,7 @@ Testing the GPU libc library
 
 .. note::
    Running GPU tests with high parallelism is likely to cause spurious failures,
-   out of resource errors, or indefinate hangs. limiting the number of threads 
+   out of resource errors, or indefinite hangs. limiting the number of threads
    used while testing is highly recommended.
 
 .. contents:: Table of Contents

libc/docs/math/log.rst

@@ -343,7 +343,7 @@ so when `C > 2^{-M - 1}` is a power of 2, we can always choose:
 .. math::
   s = -\frac{1}{2}, \quad \text{i.e.} \quad r = \frac{1}{2}.
 
-This reduction works well to avoid catastropic cancellation happening when
+This reduction works well to avoid catastrophic cancellation happening when
 `e_x = -1`.
 
 This also works when `C = 2^{-M - 1}` if we relax the condition on `u` to