Adds a modified f2c-generated C implmentation for BLAS.

This adds an optional implementation for the BLAS library that does
not require the use of a FORTRAN compiler. It can be enabled with
EIGEN_USE_F2C_BLAS.

The C implementation uses the standard gfortran calling convention
and does not require the use of -ff2c when compiled with gfortran.

blas/fortran/complexdots.f

@@ -0,0 +1,43 @@
+      COMPLEX FUNCTION CDOTC(N,CX,INCX,CY,INCY)
+      INTEGER INCX,INCY,N
+      COMPLEX CX(*),CY(*)
+      COMPLEX RES
+      EXTERNAL CDOTCW
+      
+      CALL CDOTCW(N,CX,INCX,CY,INCY,RES)
+      CDOTC = RES
+      RETURN
+      END
+      
+      COMPLEX FUNCTION CDOTU(N,CX,INCX,CY,INCY)
+      INTEGER INCX,INCY,N
+      COMPLEX CX(*),CY(*)
+      COMPLEX RES
+      EXTERNAL CDOTUW
+      
+      CALL CDOTUW(N,CX,INCX,CY,INCY,RES)
+      CDOTU = RES
+      RETURN
+      END
+      
+      DOUBLE COMPLEX FUNCTION ZDOTC(N,CX,INCX,CY,INCY)
+      INTEGER INCX,INCY,N
+      DOUBLE COMPLEX CX(*),CY(*)
+      DOUBLE COMPLEX RES
+      EXTERNAL ZDOTCW
+      
+      CALL ZDOTCW(N,CX,INCX,CY,INCY,RES)
+      ZDOTC = RES
+      RETURN
+      END
+      
+      DOUBLE COMPLEX FUNCTION ZDOTU(N,CX,INCX,CY,INCY)
+      INTEGER INCX,INCY,N
+      DOUBLE COMPLEX CX(*),CY(*)
+      DOUBLE COMPLEX RES
+      EXTERNAL ZDOTUW
+      
+      CALL ZDOTUW(N,CX,INCX,CY,INCY,RES)
+      ZDOTU = RES
+      RETURN
+      END