src/sage/matrix/matrix1.pyx: needs sage.libs.giac -> needs giac

Some tests in this file use the giac pexpect interface but are tagged
with "needs sage.libs.giac". Now that we have a feature for the giac
executable, "needs giac" is more appropriate.

Author: orlitzky

src/sage/matrix/matrix1.pyx

@@ -216,21 +216,21 @@ cdef class Matrix(Matrix0):
         EXAMPLES::
 
             sage: M = matrix(ZZ, 2, range(4))
-            sage: giac(M)                                                               # needs sage.libs.giac
+            sage: giac(M)                                                               # needs giac
             [[0,1],[2,3]]
 
             sage: M = matrix(QQ, 3, [1,2,3, 4/3,5/3,6/4, 7,8,9])
-            sage: giac(M)                                                               # needs sage.libs.giac
+            sage: giac(M)                                                               # needs giac
             [[1,2,3],[4/3,5/3,3/2],[7,8,9]]
 
             sage: P.<x> = ZZ[]
             sage: M = matrix(P, 2, [-9*x^2-2*x+2, x-1, x^2+8*x, -3*x^2+5])
-            sage: giac(M)                                                               # needs sage.libs.giac
+            sage: giac(M)                                                               # needs giac
             [[-9*sageVARx^2-2*sageVARx+2,sageVARx-1],[sageVARx^2+8*sageVARx,-3*sageVARx^2+5]]
 
             sage: y = var('y')                                                          # needs sage.symbolic
             sage: M = matrix(SR, 2, [y+sin(y), y - 4, 1/y, dilog(y)])                   # needs sage.symbolic
-            sage: giac(M).det().sage()                                                  # needs sage.libs.giac sage.symbolic
+            sage: giac(M).det().sage()                                                  # needs giac sage.symbolic
             (y^2*dilog(y) + y*dilog(y)*sin(y) - y + 4)/y
         """
         s = ','.join('[' + ','.join(cf._giac_init_() for cf in row) + ']'