Fix build with GCC 11.2

--- libenctain/botan-1.6/include/base.h
+++ libenctain/botan-1.6/include/base.h
@@ -27,8 +27,8 @@ class SymmetricAlgorithm
 
       virtual std::string name() const = 0;
 
-      void set_key(const SymmetricKey&) throw(Invalid_Key_Length);
-      void set_key(const byte[], u32bit) throw(Invalid_Key_Length);
+      void set_key(const SymmetricKey&);
+      void set_key(const byte[], u32bit);
       bool valid_keylength(u32bit) const;
       SymmetricAlgorithm(u32bit, u32bit, u32bit);
       virtual ~SymmetricAlgorithm() {}
@@ -156,7 +156,7 @@ class EntropySource
 class RandomNumberGenerator
    {
    public:
-      virtual void randomize(byte[], u32bit) throw(PRNG_Unseeded) = 0;
+      virtual void randomize(byte[], u32bit) = 0;
       virtual bool is_seeded() const { return true; }
       virtual void clear() throw() {};
 
--- libenctain/botan-1.6/include/randpool.h
+++ libenctain/botan-1.6/include/randpool.h
@@ -17,7 +17,7 @@ namespace Botan {
 class Randpool : public RandomNumberGenerator
    {
    public:
-      void randomize(byte[], u32bit) throw(PRNG_Unseeded);
+      void randomize(byte[], u32bit);
       bool is_seeded() const;
       void clear() throw();
       std::string name() const;
--- libenctain/botan-1.6/include/x931_rng.h
+++ libenctain/botan-1.6/include/x931_rng.h
@@ -17,7 +17,7 @@ namespace Botan {
 class ANSI_X931_RNG : public RandomNumberGenerator
    {
    public:
-      void randomize(byte[], u32bit) throw(PRNG_Unseeded);
+      void randomize(byte[], u32bit);
       bool is_seeded() const;
       void clear() throw();
       std::string name() const;
--- libenctain/botan-1.6/src/base.cpp
+++ libenctain/botan-1.6/src/base.cpp
@@ -37,7 +37,6 @@ bool SymmetricAlgorithm::valid_keylength(u32bit length) const
 * Set the key                                    *
 *************************************************/
 void SymmetricAlgorithm::set_key(const SymmetricKey& algo_key)
-   throw(Invalid_Key_Length)
    {
    set_key(algo_key.begin(), algo_key.length());
    }
@@ -46,7 +45,6 @@ void SymmetricAlgorithm::set_key(const SymmetricKey& algo_key)
 * Set the key                                    *
 *************************************************/
 void SymmetricAlgorithm::set_key(const byte algo_key[], u32bit length)
-   throw(Invalid_Key_Length)
    {
    if(!valid_keylength(length))
       throw Invalid_Key_Length(name(), length);
--- libenctain/botan-1.6/src/randpool.cpp
+++ libenctain/botan-1.6/src/randpool.cpp
@@ -38,7 +38,7 @@ SecureVector<byte> randpool_prf(MessageAuthenticationCode* mac,
 /*************************************************
 * Generate a buffer of random bytes              *
 *************************************************/
-void Randpool::randomize(byte out[], u32bit length) throw(PRNG_Unseeded)
+void Randpool::randomize(byte out[], u32bit length)
    {
    if(!is_seeded())
       throw PRNG_Unseeded(name());
--- libenctain/botan-1.6/src/x931_rng.cpp
+++ libenctain/botan-1.6/src/x931_rng.cpp
@@ -15,7 +15,7 @@ namespace Botan {
 /*************************************************
 * Generate a buffer of random bytes              *
 *************************************************/
-void ANSI_X931_RNG::randomize(byte out[], u32bit length) throw(PRNG_Unseeded)
+void ANSI_X931_RNG::randomize(byte out[], u32bit length)
    {
    if(!is_seeded())
       throw PRNG_Unseeded(name());