Clean-up and gitignore a.out.

.gitignore

@@ -4,6 +4,7 @@
 
 # Configure stage files
 .deps
+/a.out
 /config.log
 /config.status
 /config/config.h

configure.ac

@@ -12,12 +12,16 @@ AM_EXTRA_RECURSIVE_TARGETS([doc install-doc man install-man])
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
 LT_INIT([pic-only])
+dnl Clean up after Libtool checks for C compiler:
+rm -f a.out
 
 AC_PROG_CC_C99
 AS_VAR_IF([ac_cv_prog_cc_c99], [no],
   [AC_MSG_FAILURE([C compiler does not support ISO C99])])
 
 AC_PROG_FC
+dnl Clean up after Libtool checks for Fortran compiler:
+rm -f a.out
 AC_LANG_PUSH([Fortran])
 dnl Automake does not trace AC_FC_PP_SRCEXT/ACX_FC_PP_SRCEXT and therefore
 dnl does not add their results to the compilation rules. But AC_FC_SRCEXT is