Here's one way if you know the line numbers are 7 and 11:

$ perl -e 'open FH,"soversions.mk";print( (<FH>)[6,10])'
all-sonames+=libdl=libdl.so$(libdl.so-version)
all-sonames+=libresolv=libresolv.so$(libresolv.so-version)
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The (<FH>)[6,10] construct is a slice over the array of lines in the file. They are offset to allow for the usual convention for line counting in a file.

After Compline,
Zaxo