Finish converting GSL to absl::Span

One less dependency.

Change-Id: Iaac25a3c1312a21a8a2b77b8cfee2463bdb51196
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/motors/print/semihosting.cc b/motors/print/semihosting.cc
index 799b928..13bd78b 100644
--- a/motors/print/semihosting.cc
+++ b/motors/print/semihosting.cc
@@ -1,5 +1,6 @@
 #include "motors/print/semihosting.h"
 
+#include "absl/types/span.h"
 #include "motors/core/semihosting.h"
 
 namespace frc971 {
@@ -11,11 +12,12 @@
 }
 
 extern "C" int _write(const int /*file*/, char *const ptr, const int len) {
-  semihosting::Write operation{2 /* stderr */, gsl::span<const char>(ptr, len)};
+  semihosting::Write operation{2 /* stderr */,
+                               absl::Span<const char>(ptr, len)};
   return len - operation.Execute();
 }
 
-int SemihostingPrinting::WriteStdout(gsl::span<const char> buffer) {
+int SemihostingPrinting::WriteStdout(absl::Span<const char> buffer) {
   semihosting::Write operation{2 /* stderr */, buffer};
   return buffer.size() - operation.Execute();
 }