[gdb/testsuite] Fix timeout in gdb.fortran/info-types.exp

When running the testsuite in an enviroment that simulates a stressed system,
I ran into a timeout in test-case gdb.fortran/info-types.exp:
...
(gdb) info types^M
FAIL: gdb.fortran/info-types.exp: info types (timeout)
...

This is mainly due the presence of glibc debug info.

With it installed, I get:
...
$ time gdb -q -batch -x outputs/gdb.fortran/info-types/gdb.in.1 > /dev/null
real	0m35.969s
user	0m38.231s
sys	0m1.007s
...
and without:
...
$ time gdb -q -batch -x outputs/gdb.fortran/info-types/gdb.in.1 > /dev/null
real	0m4.782s
user	0m5.014s
sys	0m0.304s
...

Fix this by not running to main, which gets us:
...
$ time gdb -q -batch -x outputs/gdb.fortran/info-types/gdb.in.1 > /dev/null
real	0m0.808s
user	0m0.789s
sys	0m0.137s
...

Likewise in gdb.mi/mi-sym-info.exp and gdb.mi/mi-complete.exp.

Tested on x86_64-linux.

Approved-By: Tom Tromey <tom@tromey.com>

gdb/testsuite/gdb.fortran/info-types.exp

@@ -27,10 +27,8 @@ if { [prepare_for_testing "failed to prepare" $testfile \
     return -1
 }
 
-if { ![fortran_runto_main] } {
-    perror "Could not run to main."
-    return
-}
+# Don't run to main to avoid increasing the search scope to include
+# debug info of shared libraries like libc, libgcc, libgfortran etc.
 
 set integer4 [fortran_int4]
 set integer8 [fortran_int8]

gdb/testsuite/gdb.mi/mi-complete.exp

@@ -28,7 +28,8 @@ if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debu
 
 mi_clean_restart $binfile
 
-mi_runto_main
+# Don't run to main to avoid increasing the search scope to include
+# debug info of shared libraries like glibc, libgcc, etc.
 
 mi_gdb_test "1-complete br" \
             "1\\^done,completion=\"break\",matches=\\\[.*\"break\",.*\"break-range\".*\\\],max_completions_reached=\"0\"" \

gdb/testsuite/gdb.mi/mi-sym-info.exp

@@ -35,7 +35,8 @@ if {[build_executable "failed to prepare" ${testfile} \
 
 mi_clean_restart $binfile
 
-mi_runto_main
+# Don't run to main to avoid increasing the search scope to include
+# debug info of shared libraries like libc, libgcc, etc.
 
 set qstr "\"\[^\"\]+\""
 set fun_re \