BUILD: On PSP use -O2 to fix compiling with new toolchain

-O2 works, but the updated psp compiler doesn't compile
with -O3. It gives the error
```
graphics/macgui/macwindowmanager.cpp: In member function 'void Graphics::MacWindowManager::passPalette(const byte*, uint)':
graphics/macgui/macwindowmanager.cpp:517:1: error: unrecognizable insn:
 }
 ^
(insn 139 138 140 23 (set (reg:SI 294)
        (if_then_else:SI (ne:CC (reg:CC 67 $fcc0)
                (const_int 0 [0]))
            (reg/v:SI 256 [ di ])
            (reg/v:SI 229 [ di ]))) -1
     (nil))
graphics/macgui/macwindowmanager.cpp:517:1: internal compiler error: in extract_insn, at recog.c:2202
```

1 files changed, 1 insertions, 1 deletions

diff --git a/configure b/configure
index 879c5adbb8..c1c4b85572 100755
--- a/configure
+++ b/configure
@@ -2869,7 +2869,7 @@ case $_host_os in
 		add_line_to_config_h "#define PREFIX \"${prefix}\""
 		;;
 	psp)
-		_optimization_level=-O3
+		_optimization_level=-O2
 		append_var CXXFLAGS "-I$PSPSDK/include"
 		# FIXME: Why is the following in CXXFLAGS and not in DEFINES? Change or document this.
 		append_var CXXFLAGS "-D_PSP_FW_VERSION=150"