utils: Add FastStrcmp.h

Move existing fast<str*cmp> templates for general use, pulled from
the implementation used in logd that dealt with speed through cache
locality and subroutine call mitigation.  Rename to fastcmp.

Test: logd-benchmarks and based on manual profiling from the past
Bug: 31456426
Change-Id: Ic62f4a437fc3e06ffdeaae73a6f34e197957a6b0
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
index f5c60c7..ec91f2a 100644
--- a/logd/LogBufferElement.cpp
+++ b/logd/LogBufferElement.cpp
@@ -89,7 +89,7 @@
         size_t name_len = strlen(name);
         // KISS: ToDo: Only checks prefix truncated, not suffix, or both
         if ((retval_len < name_len)
-                && !fast<strcmp>(retval, name + name_len - retval_len)) {
+                && !fastcmp<strcmp>(retval, name + name_len - retval_len)) {
             free(retval);
             retval = name;
         } else {