gdb/testsuite: remove get_compiler_info calls from gdb.exp and dwarf.exp

We don't need to call get_compiler_info before calling
test_compiler_info; test_compiler_info includes a call to
get_compiler_info.

This commit cleans up lib/gdb.exp and lib/dwarf.exp a little by
removing some unneeded calls to get_compiler_info.  We could do the
same cleanup throughout the testsuite, but I'm leaving that for
another day.

There should be no change in the test results after this commit.
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index b05fdd5..3d0ea83 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -110,14 +110,6 @@
 	set binfile $executable
     }
 
-    set info_options ""
-    if { [lsearch -exact $options "c++"] >= 0 } {
-	set info_options "c++"
-    }
-    if [get_compiler_info ${info_options}] {
-        return -1
-    }
-
     set func gdb_compile
     if {[lsearch -regexp $options \
 	     {^(pthreads|shlib|shlib_pthreads|openmp)$}] != -1} {
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 7b11dab..c9a30d8 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -3238,10 +3238,6 @@
     }
 
     # Make sure we have a compiler that understands altivec.
-    if [get_compiler_info] {
-       warning "Could not get compiler info"
-       return 1
-    }
     if [test_compiler_info gcc*] {
         set compile_flags "additional_flags=-maltivec"
     } elseif [test_compiler_info xlc*] {
@@ -3357,10 +3353,6 @@
     }
 
     # Make sure we have a compiler that understands altivec.
-    if [get_compiler_info] {
-       warning "Could not get compiler info"
-       return 1
-    }
     if [test_compiler_info gcc*] {
         set compile_flags "additional_flags=-mvsx"
     } elseif [test_compiler_info xlc*] {
@@ -4781,11 +4773,8 @@
     } elseif { [lsearch -exact $options "f90"] >= 0 } {
 	set info_options "f90"
     }
-    if [get_compiler_info ${info_options}] {
-       return -1
-    }
 
-    switch -glob [test_compiler_info] {
+    switch -glob [test_compiler_info "" ${info_options}] {
         "xlc-*" {
             lappend obj_options "additional_flags=-qpic"
         }
@@ -6964,16 +6953,6 @@
 
     set binfile [standard_output_file $executable]
 
-    set info_options ""
-    if { [lsearch -exact $options "c++"] >= 0 } {
-	set info_options "c++"
-    } elseif { [lsearch -exact $options "f90"] >= 0 } {
-	set info_options "f90"
-    }
-    if [get_compiler_info ${info_options}] {
-        return -1
-    }
-
     set func gdb_compile
     set func_index [lsearch -regexp $options {^(pthreads|shlib|shlib_pthreads|openmp)$}]
     if {$func_index != -1} {