Trac #33201: Fix "referenced before assignment" warnings in matrices

{{{
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:283:19: local variable 'd'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:285:18: local variable 'd'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:289:11: local variable 'd'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:297:14: local variable 'one'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:298:14: local variable 'zero'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:305:58: local variable 'one'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:306:65: local variable 'zero'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:309:57: local variable 'one'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:310:65: local variable 'zero'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:323:11: local variable 'one'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:324:11: local variable 'zero'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:328:30: local variable 'one'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:329:15: local variable 'zero'
referenced before assignment
[sagelib-9.5.rc2] warning:
sage/matrix/matrix_modn_dense_template.pxi:283:19: local variable 'd'
referenced before assignment
}}}

URL: https://trac.sagemath.org/33201
Reported by: mjo
Ticket author(s): Michael Orlitzky
Reviewer(s): Dima Pasechnik

Author: Release Manager

src/sage/matrix/matrix_modn_dense_template.pxi

@@ -299,7 +299,7 @@ cdef inline celement linbox_matrix_matrix_multiply(celement modulus, celement* a
     C = A*B
     """
     cdef ModField *F = new ModField(<long>modulus)
-    cdef ModField.Element one, zero
+    cdef ModField.Element one = 0, zero = 0
     F[0].init(one, <int>1)
     F[0].init(zero, <int>0)
 
@@ -327,7 +327,7 @@ cdef inline int linbox_matrix_vector_multiply(celement modulus, celement* C, cel
     C = A*v
     """
     cdef ModField *F = new ModField(<long>modulus)
-    cdef ModField.Element one, zero
+    cdef ModField.Element one = 0, zero = 0
     F.init(one, <int>1)
     F.init(zero, <int>0)