Use float in e_sqrt.c

The type used within e_sqrt.c(__slow_ieee754_sqrtf) was, unnecessarily and
likely inadvertently, double.  float is not only appropriate, but also
more efficient, avoiding the need for the compiler to emit a
round-to-single-precision instruction.

This is the difference in compiled code:
 0000000000000000 <__ieee754_sqrtf>:
    0:  2c 08 20 ec     fsqrts  f1,f1
-   4:  18 08 20 fc     frsp    f1,f1
-   8:  20 00 80 4e     blr
+   4:  20 00 80 4e     blr

(Found by Anton Blanchard.)

1 files changed, 5 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index f12f435b26..6f1d967f62 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-02-11  Paul A. Clarke  <pc@us.ibm.com>
+
+	* sysdeps/powerpc/fpu/e_sqrt.c (__slow_ieee754_sqrtf):
+	Use float instead of double.
+
 2019-02-11  TAMUKI Shoichi  <tamuki@linet.gr.jp>
 
 	* time/strftime_l.c: Fix a few whitespace arrangement inconsistencies.