Fix ctl::string_view const iteration issue

Author: jart

ctl/string_view.h

@@ -109,12 +109,12 @@ struct string_view
         return p[n - 1];
     }
 
-    constexpr const_iterator begin() noexcept
+    constexpr const_iterator begin() const noexcept
     {
         return p;
     }
 
-    constexpr const_iterator end() noexcept
+    constexpr const_iterator end() const noexcept
     {
         return p + n;
     }

test/ctl/string_view_test.cc

@@ -16,6 +16,7 @@
 // TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 // PERFORMANCE OF THIS SOFTWARE.
 
+#include "ctl/string.h"
 #include "ctl/string_view.h"
 #include "libc/mem/leaks.h"
 #include "libc/str/str.h"
@@ -172,5 +173,14 @@ main(int argc, char* argv[])
             return 32;
     }
 
+    {
+        ctl::string b;
+        const ctl::string_view s = "hi";
+        for (char c : s)
+            b += c;
+        if (b != "hi")
+            return 2;
+    }
+
     CheckForMemoryLeaks();
 }