Add missing noexcept clauses

Note that the changes in memory.pxd are identical to upstream changes
made as part of sagemath/cysignals#187

memory_allocator/memory.pxd

@@ -35,35 +35,35 @@ cdef extern from *:
     int unlikely(int) nogil  # Defined by Cython
 
 
-cdef inline void* sig_malloc "sig_malloc"(size_t n) nogil:
+cdef inline void* sig_malloc "sig_malloc"(size_t n) noexcept nogil:
     sig_block()
     cdef void* ret = malloc(n)
     sig_unblock()
     return ret
 
 
-cdef inline void* sig_realloc "sig_realloc"(void* ptr, size_t size) nogil:
+cdef inline void* sig_realloc "sig_realloc"(void* ptr, size_t size) noexcept nogil:
     sig_block()
     cdef void* ret = realloc(ptr, size)
     sig_unblock()
     return ret
 
 
-cdef inline void* sig_calloc "sig_calloc"(size_t nmemb, size_t size) nogil:
+cdef inline void* sig_calloc "sig_calloc"(size_t nmemb, size_t size) noexcept nogil:
     sig_block()
     cdef void* ret = calloc(nmemb, size)
     sig_unblock()
     return ret
 
 
-cdef inline void sig_free "sig_free"(void* ptr) nogil:
+cdef inline void sig_free "sig_free"(void* ptr) noexcept nogil:
     sig_block()
     free(ptr)
     sig_unblock()
 
 
 @cython.cdivision(True)
-cdef inline size_t mul_overflowcheck(size_t a, size_t b) nogil:
+cdef inline size_t mul_overflowcheck(size_t a, size_t b) noexcept nogil:
     """
     Return a*b, checking for overflow. Assume that a > 0.
     If overflow occurs, return <size_t>(-1).

memory_allocator/memory_allocator.pxd

@@ -6,7 +6,7 @@ cdef extern from *:
     int unlikely(int) nogil  # defined by Cython
 
 
-cdef inline void* align(void* ptr, size_t alignment):
+cdef inline void* align(void* ptr, size_t alignment) noexcept:
     """
     Round up ``ptr`` to the nearest multiple of ``alignment``, which
     must be a power of 2

memory_allocator/signals.pxd

@@ -3,8 +3,8 @@
 # Usage of ``sig_block`` / ``sig_unblock`` is not necesarry for ``MemoryAllocator``:
 # One should not wrap its methods with ``sig_on`` ... ``sig_off`` anyway.
 
-cdef inline void sig_block() nogil:
+cdef inline void sig_block() noexcept nogil:
     pass
 
-cdef inline void sig_unblock() nogil:
+cdef inline void sig_unblock() noexcept nogil:
     pass