src/lib: remove redundant ternary operators

Closes #15435

lib/vauth/digest_sspi.c

@@ -69,7 +69,7 @@ bool Curl_auth_is_digest_supported(void)
     Curl_pSecFn->FreeContextBuffer(SecurityPackage);
   }
 
-  return (status == SEC_E_OK ? TRUE : FALSE);
+  return (status == SEC_E_OK);
 }
 
 /*

lib/vauth/krb5_sspi.c

@@ -64,7 +64,7 @@ bool Curl_auth_is_gssapi_supported(void)
     Curl_pSecFn->FreeContextBuffer(SecurityPackage);
   }
 
-  return (status == SEC_E_OK ? TRUE : FALSE);
+  return (status == SEC_E_OK);
 }
 
 /*

lib/vauth/ntlm.c

@@ -485,7 +485,7 @@ CURLcode Curl_auth_create_ntlm_type3_message(struct Curl_easy *data,
   unsigned char ntresp[24]; /* fixed-size */
   unsigned char *ptr_ntresp = &ntresp[0];
   unsigned char *ntlmv2resp = NULL;
-  bool unicode = (ntlm->flags & NTLMFLAG_NEGOTIATE_UNICODE) ? TRUE : FALSE;
+  bool unicode = (ntlm->flags & NTLMFLAG_NEGOTIATE_UNICODE);
   /* The fixed hostname we provide, in order to not leak our real local host
      name. Copy the name used by Firefox. */
   static const char host[] = "WORKSTATION";

lib/vauth/ntlm_sspi.c

@@ -63,7 +63,7 @@ bool Curl_auth_is_ntlm_supported(void)
     Curl_pSecFn->FreeContextBuffer(SecurityPackage);
   }
 
-  return (status == SEC_E_OK ? TRUE : FALSE);
+  return (status == SEC_E_OK);
 }
 
 /*

lib/vauth/spnego_sspi.c

@@ -67,7 +67,7 @@ bool Curl_auth_is_spnego_supported(void)
   }
 
 
-  return (status == SEC_E_OK ? TRUE : FALSE);
+  return (status == SEC_E_OK);
 }
 
 /*

lib/vauth/vauth.c

@@ -134,8 +134,7 @@ bool Curl_auth_user_contains_domain(const char *user)
     /* Check we have a domain name or UPN present */
     char *p = strpbrk(user, "\\/@");
 
-    valid = (p != NULL && p > user && p < user + strlen(user) - 1 ? TRUE :
-                                                                    FALSE);
+    valid = (p != NULL && p > user && p < user + strlen(user) - 1);
   }
 #if defined(HAVE_GSSAPI) || defined(USE_WINDOWS_SSPI)
   else