[#567] Rename MUMPS -> M

This commit can be replicated by running sed 's/MUMPS/M/g' ydbcmake/* -i then renaming all the files from MUMPS to M.

Before:

$ make clean && make -j4 _ydbocto
Scanning dependencies of target _ydbocto
[  0%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoAdmin.m.o
[  0%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoCleanup.m.o
[  0%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoInit.m.o
[ 33%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoUtils.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgObjDescription.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctocurrentSchema.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgGetExpr.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgCurrentSchemas.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgRowNumber.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoplanhelpers.m.o
[ 66%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoreplace.m.o
[100%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoselect.m.o
[100%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctosqlfunctions.m.o
[100%] Building MUMPS object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoversion.m.o
[100%] Linking MUMPS shared library _ydbocto.so
[100%] Built target _ydbocto

After:

$ make clean && make -j4 _ydbocto
Scanning dependencies of target _ydbocto
[ 33%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoCleanup.m.o
[ 33%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoInit.m.o
[ 33%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoAdmin.m.o
[ 33%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoUtils.m.o
[ 33%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctocurrentSchema.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgGetExpr.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgCurrentSchemas.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgObjDescription.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctopgRowNumber.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoplanhelpers.m.o
[ 66%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoreplace.m.o
[100%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoselect.m.o
[100%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctosqlfunctions.m.o
[100%] Building M object src/CMakeFiles/_ydbocto.dir/aux/_ydboctoversion.m.o
[100%] Linking M shared library _ydbocto.so
[100%] Built target _ydbocto

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