gdb: Force use of float version of log10

gdb: Force use of float version of log10

This commit:

  commit aa17805fb9a3a1983a510ba425b682fba03410c2
  Date:   Sat Aug 31 23:44:40 2019 +0100

      gdb: Have 'maint info sections' print all sections again

introduced a use of log10 that took an int as a parameter.
Unfortunately this was causing a compilation error on Solaris, see:

  https://sourceware.org/ml/gdb-patches/2019-09/msg00230.html
  https://sourceware.org/ml/gdb-patches/2019-09/msg00231.html

because there was only a float, double, or long double version of
log10, and the compiler doesn't know which to choose.

This commit should resolve this issue by casting the argument to
float.

gdb/ChangeLog:

	* maint.c (maint_print_section_data::maint_print_section_data):
	Force use of 'float log10 (float)' by casting the argument to
	float.