MdeModulePkg: Fix buffer overflow in MergeMemoryMap #5427

Job	Run time
Analyze (ArmPkg, IA32,X64)	4m 46s
Analyze (CryptoPkg, IA32)	14m 39s
Analyze (CryptoPkg, X64)	19m 5s
Analyze (DynamicTablesPkg, IA32,X64)	10m 24s
Analyze (FatPkg, IA32,X64)	10m 53s
Analyze (FmpDevicePkg, IA32,X64)	9m 11s
Analyze (IntelFsp2Pkg, IA32,X64)	8m 45s
Analyze (IntelFsp2WrapperPkg, IA32,X64)	12m 1s
Analyze (MdeModulePkg, IA32)	15m 54s
Analyze (MdeModulePkg, X64)	12m 51s
Analyze (MdePkg, IA32,X64)	9m 15s
Analyze (PcAtChipsetPkg, IA32,X64)	10m 58s
Analyze (PrmPkg, IA32,X64)	7m 30s
Analyze (SecurityPkg, IA32,X64)	9m 47s
Analyze (ShellPkg, IA32,X64)	10m 17s
Analyze (SourceLevelDebugPkg, IA32,X64)	11m 27s
Analyze (StandaloneMmPkg, IA32,X64)	11m 18s
Analyze (UefiCpuPkg, IA32,X64)	12m 11s
Analyze (UnitTestFrameworkPkg, IA32,X64)	10m 19s
	3h 31m 31s

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