Add OMR UnsafeSubexpressionRemover.cpp to UMA makefile

The new OMR compiler source file UnsafeSubexpressionRemover.cpp needs to
be included in OpenJ9's UMA makefile in order to build OpenJ9
successfully in that build environment.

Signed-off-by:  Henry Zongaro <zongaro@ca.ibm.com>

Author: hzongaro

runtime/compiler/build/files/common.mk.ftl

@@ -241,6 +241,7 @@ JIT_PRODUCT_BACKEND_SOURCES+=\
     omr/compiler/optimizer/TranslateTable.cpp \
     omr/compiler/optimizer/TrivialDeadBlockRemover.cpp \
     omr/compiler/optimizer/UnionBitVectorAnalysis.cpp \
+    omr/compiler/optimizer/UnsafeSubexpressionRemover.cpp \
     omr/compiler/optimizer/UseDefInfo.cpp \
     omr/compiler/optimizer/ValueNumberInfo.cpp \
     omr/compiler/optimizer/ValuePropagationCommon.cpp \