tinystdio: ungetc decrements file position indicator correctly #20

Job	Run time
cache-maker	15s
cmake-linux (./.github/do-cmake-linux -DCMAKE_BUILD_TYPE=RelWithDebInfo)	9m 48s
cmake-linux (./.github/do-cmake-linux -DCMAKE_BUILD_TYPE=MinSizeRel)	9m 15s
cmake-linux (-D__IO_FLOAT=y -D_IO_FLOAT_EXACT=n -D_WANT_IO_LONG_LONG=y -D_MB_CAPABLE=y -D_WANT_IO...	9m 44s
cmake-linux (-D__IO_FLOAT=y -D_IO_FLOAT_EXACT=n -D_WANT_IO_LONG_LONG=y -D_MB_CAPABLE=y -D_WANT_IO...	9m 34s
minsize-linux (./.github/do-linux)	1h 54m 22s
minsize-linux (-Dio-float-exact=false -Dio-long-long=true -Dio-percent-b=true -Dio-long-double=tr...	1h 33m 12s
minsize-linux (-Dformat-default=integer -Dfreestanding=true -Dposix-io=false -Dnewlib-obsolete-ma...	1h 50m 0s
minsize-linux (-Dtinystdio=false, ./.github/do-linux)	1h 10m 10s
minsize-linux (-Dtinystdio=false -Dnewlib-io-float=true -Dio-long-long=true -Dio-long-double=true...	53m 50s
release-linux (./.github/do-linux)	1h 59m 55s
release-linux (-Dio-float-exact=false -Dio-long-long=true -Dio-percent-b=true -Dio-long-double=tr...	1h 37m 27s
release-linux (-Dformat-default=integer -Dfreestanding=true -Dposix-io=false -Dnewlib-obsolete-ma...	1h 55m 33s
release-linux (-Dtinystdio=false, ./.github/do-linux)	1h 16m 16s
release-linux (-Dtinystdio=false -Dnewlib-io-float=true -Dio-long-long=true -Dio-long-double=true...	55m 46s
	15h 45m 7s

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