To allow compiling with gcc versions older than 4.9

This was added in #1046 citing a problem with mingw, but in effect it quietly reduces thread safety on all non-Windows platforms (while -fopenmp is already disabled for Windows builds through the toplevel Makefile.system). Removing the filter fixes #1425

From Reference-LAPACK issue 228, remove spurious EXTERNAL reference to unused and nonexistent function xLACGV that could cause linking problems.

Inf values in the input vector will survive rescaling, causing an infinite loop. The value of 1000 is arbitrarily chosen as a large but finite value with the intention to never interfere with regular calculations.

* Fix integer overflow in DBDSQR

As noted in lapack issue 135, an integer overflow in the calculation of the iteration limit could lead to an immediate return without any iterations having been performed if the input matrix is sufficiently big.

* Fix integer overflow in SBDSQR

As noted in lapack issue 135, an integer overflow in the calculation of the iteration limit could lead to an immediate return without any iterations having been performed if the input matrix is sufficiently big.

* Fix integer overflow in threshold calculation

Related to lapack issue 135, the threshold calculation can overflow as well as the multiplication is evaluated from left to right.
Without explicit parentheses, the calculation would overflow for N >= 18919

* Fix integer overflow in threshold calculation

Related to lapack issue 135, the threshold calculation can overflow as well as the multiplication is evaluated from left to right.
Without explicit parentheses, the calculation would overflow for N >= 18919

EXTERNAL declaration of subroutines missed a comma before the continuation line,
causing a strange run-together name to appear in the object when compiled with ifort.

EXTERNAL declaration of subroutines missed a comma before the continuation line,
causing a strange run-together name to appear in the object when compiled with ifort.

EXTERNAL declaration of subroutines missed a comma before the continuation line,
causing a strange run-together name to appear in the object when compiled with ifort.

EXTERNAL declaration of subroutines missed a comma before the continuation line,
causing a strange run-together name to appear in the object when compiled with ifort.

Trivial typo correction (ZERBLA => XERBLA) to fix #910

Based on 3.4.2 version, apply patch.for_lapack-3.4.2.