Fix Valgrind-reported invalid read
Fix Valgrind-reported invalid read

test_buffer_run() pops a message before printing it, when it should be
doing the reverse.

> 410 errors in context 6 of 6:
> Invalid read of size 1
>    at 0x4C33384: strlen (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
>    by 0x5D624D2: vfprintf (vfprintf.c:1643)
>    by 0x5D6367F: buffered_vfprintf (vfprintf.c:2329)
>    by 0x5D60725: vfprintf (vfprintf.c:1301)
>    by 0x5D69F25: printf (printf.c:33)
>    by 0x14A35A: test_buffer_run (csound_message_buffer_test.c:58)
>    by 0x4E40D36: run_single_test.constprop.5 (TestRun.c:991)
>    by 0x4E4106F: run_single_suite.constprop.4 (TestRun.c:876)
>    by 0x4E413BD: CU_run_all_tests (TestRun.c:367)
>    by 0x14A43E: main (csound_message_buffer_test.c:93)
>  Address 0xc7a99cd is 13 bytes inside a block of size 45 free'd
>    at 0x4C30FDB: free (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
>    by 0x1518CD: csoundPopFirstMessage (csound.c:4319)
>    by 0x14A342: test_buffer_run (csound_message_buffer_test.c:57)
>    by 0x4E40D36: run_single_test.constprop.5 (TestRun.c:991)
>    by 0x4E4106F: run_single_suite.constprop.4 (TestRun.c:876)
>    by 0x4E413BD: CU_run_all_tests (TestRun.c:367)
>    by 0x14A43E: main (csound_message_buffer_test.c:93)
>  Block was alloc'd at
>    at 0x4C2FDAF: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
>    by 0x151AD9: csoundMessageBufferCallback_1_ (csound.c:4384)
>    by 0x14DBE1: csoundMessage (csound.c:2560)
>    by 0x105CDA54: csoundModuleInit (rtalsa.c:1909)
>    by 0x22FB82: csoundInitModule (csmodule.c:609)
>    by 0x22FD3D: csoundInitModules (csmodule.c:664)
>    by 0x231F9C: csoundStart (main.c:459)
>    by 0x14A2E6: test_buffer_run (csound_message_buffer_test.c:50)
>    by 0x4E40D36: run_single_test.constprop.5 (TestRun.c:991)
>    by 0x4E4106F: run_single_suite.constprop.4 (TestRun.c:876)
>    by 0x4E413BD: CU_run_all_tests (TestRun.c:367)
>    by 0x14A43E: main (csound_message_buffer_test.c:93)

csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,csound/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound